I've been using my laptop with an external LCD monitor attached to it at work (Philips 201E). And at home with a different external monitor (Samsung 2032BW). I have an ATI graphics card (HD3450), with Ati Catalyst drivers enabled and I'm using the Single display desktop (Multi-Desktop) seeting. At work I have the external monitor on the left and laptop on the right, while at home the other way around. So when I switch between the two setups, I just needed to go to Ati Catalyst Control Center, change the order of the displays, change the resolution (Home - 1680x1050, Work - 1440x900), reboot and it was all fine.

But since a while it doesn't work properly anymore:

At home it still works fine. At work it doesn't work. Sometimes it works for some reason, after a few resolution/setting changes in ACCC and reboots... it's very strange and annoying.

With the home monitor I can see the whole bootup process on both monitors (laptop + LCD) and it always just works fine. With the work monitor on the external LCD monitor I just see "No video input" until I get to the login screen, then it shows up there as well. But after login it will either:

1. Flicker a few times, but then work OK.
2. Or (more often) Flicker once and then go back to "No video input" again. I usually end up rebooting a few times until it works.

Does anyone have any idea for fixing it?

This is my xorg.conf currently:

Section "ServerLayout"
    Identifier     "amdcccle Layout"
    Screen      0  "amdcccle-Screen[6]-0" 0 0
    Screen         "amdcccle-Screen[6]-1" 1280 0
EndSection

Section "Files"
EndSection

Section "Module"
    Load  "glx"
EndSection

Section "ServerFlags"
    Option      "Xinerama" "off"
EndSection

Section "Monitor"
    Identifier   "0-LVDS"
    Option      "VendorName" "ATI Proprietary Driver"
    Option      "ModelName" "Generic Autodetecting Monitor"
    Option      "DPMS" "true"
    Option      "PreferredMode" "1280x768"
    Option      "TargetRefresh" "60"
    Option      "Position" "0 0"
    Option      "Rotate" "normal"
    Option      "Disable" "false"
EndSection

Section "Monitor"
    Identifier   "0-CRT1"
    Option      "VendorName" "ATI Proprietary Driver"
    Option      "ModelName" "Generic Autodetecting Monitor"
    Option      "DPMS" "true"
    Option      "TargetRefresh" "60"
    Option      "Position" "0 0"
    Option      "Rotate" "normal"
    Option      "Disable" "false"
    Option      "PreferredMode" "1440x900"
EndSection

Section "Device"
    Identifier  "Default Device"
    Driver      "fglrx"
EndSection

Section "Device"
    Identifier  "amdcccle-Device[6]-0"
    Driver      "fglrx"
    Option      "Monitor-LVDS" "0-LVDS"
    BusID       "PCI:6:0:0"
EndSection

Section "Device"
    Identifier  "amdcccle-Device[6]-1"
    Driver      "fglrx"
    Option      "Monitor-CRT1" "0-CRT1"
    BusID       "PCI:6:0:0"
    Screen      1
EndSection

Section "Screen"
    Identifier "Default Screen"
    DefaultDepth     24
    SubSection "Display"
        Virtual   2560 1024
    EndSubSection
EndSection

Section "Screen"
    Identifier "amdcccle-Screen[6]-0"
    Device     "amdcccle-Device[6]-0"
    DefaultDepth     24
    SubSection "Display"
        Viewport   0 0
        Depth     24
    EndSubSection
EndSection

Section "Screen"
    Identifier "amdcccle-Screen[6]-1"
    Device     "amdcccle-Device[6]-1"
    DefaultDepth     24
    SubSection "Display"
        Viewport   0 0
        Depth     24
    EndSubSection
EndSection