Ok, i realize I am not the only one, but I will try to provide all info possible to make it exemplary as possible and narrow down the error sources.
I have a fresh install of Ubuntu 12.04 and the suspend worked fine upon having it freshly installed but now it does not anymore.
The suspend option from the system power button on the top right works fine.
Things I did do which I don't know if they are related:
Install and remove againthe FGLRX drivers (Radeon graphic card)
Install Jupiter power managment (shutting it down is not changin anything)
Plug in and out an external display
The configuration I know of is well set:
In System Settings/Power all is set to suspend when closing lid
Double checked with dconf-editor, everything set to suspend
So, from here on I don't know how to proceed.. what are common problems that cause this error?
EDIT:
My computer model is: Samsung Series 5 14" NP530U4BI
$ sudo lspci -nn
00:00.0 Host bridge [0600]: Intel Corporation 2nd Generation Core Processor Family DRAM Controller
00:01.0 PCI bridge [0604]: Intel Corporation Xeon E3-1200/2nd Generation Core Processor Family PCI Express Root Port
00:02.0 VGA compatible controller [0300]: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller
00:16.0 Communication controller [0780]: Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1
00:1a.0 USB controller [0c03]: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2
00:1b.0 Audio device [0403]: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller
00:1c.0 PCI bridge [0604]: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1
00:1c.3 PCI bridge [0604]: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 4
00:1c.4 PCI bridge [0604]: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 5
00:1d.0 USB controller [0c03]: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1
00:1f.0 ISA bridge [0601]: Intel Corporation HM65 Express Chipset Family LPC Controller [8086:1c49] (rev 04)
00:1f.2 SATA controller [0106]: Intel Corporation 6 Series/C200 Series Chipset Family 6 port SATA AHCI Controller
00:1f.3 SMBus [0c05]: Intel Corporation 6 Series/C200 Series Chipset Family SMBus Controller [8086:1c22] (rev 04)
01:00.0 VGA compatible controller [0300]: Advanced Micro Devices [AMD] nee ATI Thames [Radeon 7500M/7600M Series]
02:00.0 Network controller [0280]: Intel Corporation Centrino Advanced-N 6230
03:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller
04:00.0 USB controller [0c03]: ASMedia Technology Inc. ASM1042 SuperSpeed USB Host Controller
