I tried to install Lubuntu 14.04.1 from a CD. First, I chose Try Lubuntu without installing which gave:

ERROR: PAE is disabled on this Pentium M
(PAE can potentially be enabled with kernel parameter "forcepae" ...

Following the description on https://help.ubuntu.com/community/PAE, I used forcepae and tried Try Lubuntu without installing again. That worked fine. dmesg | grep -i pae showed:

[    0.000000] Kernel command line: file=/cdrom/preseed/lubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- forcepae
[    0.008118] PAE forced!

On the live-CD session, I tried installing Lubuntu double clicking on the install button on the desktop. Here, the CD starts running but then stops running and nothing happens.

Next, I rebooted and tried installing Lubuntu directly from the boot menu screen using forcepae again. After a while, I receive the following error message:

The installer encountered an unrecoverable error. A desktop session will now be run so that you may investigate the problem or try installing again.

Hitting Enter brings me to the desktop. For what errors should I search? And how?

Finally, I rebooted once more and tried Check disc for defects with forcepae option; no errors have been found.

Now, I am wondering how to find the error or whether it would be better to follow advice c in https://help.ubuntu.com/community/PAE: "Move the hard disk to a computer on which the processor has PAE capability and PAE flag (that is, almost everything else than a Banias). Install the system as usual but don't add restricted drivers. After the install move the disk back."

Thanks for some hints!

Perhaps some of the following can help:

On Lubuntu 12.04:

cat /proc/cpuinfo
processor   : 0
vendor_id   : GenuineIntel
cpu family  : 6
model       : 13
model name  : Intel(R) Pentium(R) M processor 1.50GHz
stepping    : 6
microcode   : 0x17
cpu MHz     : 600.000
cache size  : 2048 KB
fdiv_bug    : no
hlt_bug     : no
f00f_bug    : no
coma_bug    : no
fpu     : yes
fpu_exception   : yes
cpuid level : 2
wp      : yes
flags       : fpu vme de pse tsc msr mce cx8 mtrr pge mca cmov clflush dts acpi mmx fxsr sse sse2 ss tm pbe up bts est tm2
bogomips    : 1284.76
clflush size    : 64
cache_alignment : 64
address sizes   : 32 bits physical, 32 bits virtual
power management:

uname -a
Linux humboldt 3.2.0-67-generic #101-Ubuntu SMP Tue Jul 15 17:45:51 UTC 2014 i686 i686 i386 GNU/Linux

lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 12.04.5 LTS
Release:    12.04
Codename:   precise

cpuid
 eax in    eax      ebx      ecx      edx
00000000 00000002 756e6547 6c65746e 49656e69
00000001 000006d6 00000816 00000180 afe9f9bf
00000002 02b3b001 000000f0 00000000 2c04307d
80000000 80000004 00000000 00000000 00000000
80000001 00000000 00000000 00000000 00000000
80000002 20202020 20202020 65746e49 2952286c
80000003 6e655020 6d756974 20295228 7270204d
80000004 7365636f 20726f73 30352e31 007a4847

Vendor ID: "GenuineIntel"; CPUID level 2

Intel-specific functions:
Version 000006d6:
Type 0 - Original OEM
Family 6 - Pentium Pro
Model 13 - 
Stepping 6
Reserved 0

Brand index: 22 [not in table]
Extended brand string: "        Intel(R) Pentium(R) M processor 1.50GHz"
CLFLUSH instruction cache line size: 8

Feature flags afe9f9bf:
FPU    Floating Point Unit
VME    Virtual 8086 Mode Enhancements
DE     Debugging Extensions
PSE    Page Size Extensions
TSC    Time Stamp Counter
MSR    Model Specific Registers
MCE    Machine Check Exception
CX8    COMPXCHG8B Instruction
SEP    Fast System Call
MTRR   Memory Type Range Registers
PGE    PTE Global Flag
MCA    Machine Check Architecture
CMOV   Conditional Move and Compare Instructions
FGPAT  Page Attribute Table
CLFSH  CFLUSH instruction
DS     Debug store
ACPI   Thermal Monitor and Clock Ctrl
MMX    MMX instruction set
FXSR   Fast FP/MMX Streaming SIMD Extensions save/restore
SSE    Streaming SIMD Extensions instruction set
SSE2   SSE2 extensions
SS     Self Snoop
TM     Thermal monitor
31     reserved

TLB and cache info:
b0: unknown TLB/cache descriptor
b3: unknown TLB/cache descriptor
02: Instruction TLB: 4MB pages, 4-way set assoc, 2 entries
f0: unknown TLB/cache descriptor
7d: unknown TLB/cache descriptor
30: unknown TLB/cache descriptor
04: Data TLB: 4MB pages, 4-way set assoc, 8 entries
2c: unknown TLB/cache descriptor

On Lubuntu 14.04.1 live-CD with forcepae:

cat /proc/cpuinfo
processor   : 0
vendor_id   : GenuineIntel
cpu family  : 6
model       : 13
model name  : Intel(R) Pentium(R) M processor 1.50GHz
stepping    : 6
microcode   : 0x17
cpu MHz     : 600.000
cache size  : 2048 KB
physical id : 0
siblings    : 1
core id     : 0
cpu cores   : 1
apicid      : 0
initial apicid  : 0
fdiv_bug    : no
f00f_bug    : no
coma_bug    : no
fpu     : yes
fpu_exception   : yes
cpuid level : 2
wp      : yes
flags       : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov clflush dts acpi mmx fxsr sse sse2 ss tm pbe bts est tm2
bogomips    : 1284.68
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 32 bits virtual
power management:

uname -a
Linux lubuntu 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:12 UTC 2014 i686    i686 i686 GNU/Linux

lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.1 LTS
Release:    14.04
Codename:   trusty

cpuid
CPU 0:
   vendor_id = "GenuineIntel"
   version information (1/eax):
      processor type  = primary processor (0)
      family          = Intel Pentium Pro/II/III/Celeron/Core/Core 2/Atom, AMD Athlon/Duron, Cyrix M2, VIA C3 (6)
      model           = 0xd (13)
      stepping id     = 0x6 (6)
      extended family = 0x0 (0)
      extended model  = 0x0 (0)
      (simple synth)  = Intel Pentium M (Dothan B1) / Celeron M (Dothan B1), 90nm
   miscellaneous (1/ebx):
      process local APIC physical ID = 0x0 (0)
      cpu count                      = 0x0 (0)
      CLFLUSH line size              = 0x8 (8)
      brand index                    = 0x16 (22)
   brand id = 0x16 (22): Intel Pentium M, .13um
   feature information (1/edx):
      x87 FPU on chip                        = true
      virtual-8086 mode enhancement          = true
      debugging extensions                   = true
      page size extensions                   = true
      time stamp counter                     = true
      RDMSR and WRMSR support                = true
      physical address extensions            = false
      machine check exception                = true
      CMPXCHG8B inst.                        = true
      APIC on chip                           = false
      SYSENTER and SYSEXIT                   = true
      memory type range registers            = true
      PTE global bit                         = true
      machine check architecture             = true
      conditional move/compare instruction   = true
      page attribute table                   = true
      page size extension                    = false
      processor serial number                = false
      CLFLUSH instruction                    = true
      debug store                            = true
      thermal monitor and clock ctrl         = true
      MMX Technology                         = true
      FXSAVE/FXRSTOR                         = true
      SSE extensions                         = true
      SSE2 extensions                        = true
      self snoop                             = true
      hyper-threading / multi-core supported = false
      therm. monitor                         = true
      IA64                                   = false
      pending break event                    = true
   feature information (1/ecx):
      PNI/SSE3: Prescott New Instructions     = false
      PCLMULDQ instruction                    = false
      64-bit debug store                      = false
      MONITOR/MWAIT                           = false
      CPL-qualified debug store               = false
      VMX: virtual machine extensions         = false
      SMX: safer mode extensions              = false
      Enhanced Intel SpeedStep Technology     = true
      thermal monitor 2                       = true
      SSSE3 extensions                        = false
      context ID: adaptive or shared L1 data  = false
      FMA instruction                         = false
      CMPXCHG16B instruction                  = false
      xTPR disable                            = false
      perfmon and debug                       = false
      process context identifiers             = false
      direct cache access                     = false
      SSE4.1 extensions                       = false
      SSE4.2 extensions                       = false
      extended xAPIC support                  = false
      MOVBE instruction                       = false
      POPCNT instruction                      = false
      time stamp counter deadline             = false
      AES instruction                         = false
      XSAVE/XSTOR states                      = false
      OS-enabled XSAVE/XSTOR                  = false
      AVX: advanced vector extensions         = false
      F16C half-precision convert instruction = false
      RDRAND instruction                      = false
      hypervisor guest status                 = false
   cache and TLB information (2):
      0xb0: instruction TLB: 4K, 4-way, 128 entries
      0xb3: data TLB: 4K, 4-way, 128 entries
      0x02: instruction TLB: 4M pages, 4-way, 2 entries
      0xf0: 64 byte prefetching
      0x7d: L2 cache: 2M, 8-way, sectored, 64 byte lines
      0x30: L1 cache: 32K, 8-way, 64 byte lines
      0x04: data TLB: 4M pages, 4-way, 8 entries
      0x2c: L1 data cache: 32K, 8-way, 64 byte lines
   extended feature flags (0x80000001/edx):
      SYSCALL and SYSRET instructions        = false
      execution disable                      = false
      1-GB large page support                = false
      RDTSCP                                 = false
      64-bit extensions technology available = false
   Intel feature flags (0x80000001/ecx):
      LAHF/SAHF supported in 64-bit mode     = false
      LZCNT advanced bit manipulation        = false
      3DNow! PREFETCH/PREFETCHW instructions = false
   brand = "        Intel(R) Pentium(R) M processor 1.50GHz"
   (multi-processing synth): none
   (multi-processing method): Intel leaf 1
   (synth) = Intel Pentium M (Dothan B1), 90nm