I've been having garbled screen problems on a Gateway LT3103u on Ubuntu for a while. I just did a fresh install of Ubuntu 11.10 and continue to have issues. I installed xubuntu-desktop in case the issues had to do with the sophisticated GNOME graphics. The problem is less bad, but it's still there. After a few minutes of using XFCE, the screen gets garbled. I assume this has something to do with the graphics card, but I don't know how to go about troubleshooting something like this. Where should I start?
Update: Here is the description of the VGA card from lspci -vvv:
01:05.0 VGA compatible controller: ATI Technologies Inc RS690M [Radeon X1200 Series] (prog-if 00 [VGA controller]) Subsystem: Acer Incorporated [ALI] Device 028c Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 64, Cache Line Size: 32 bytes Interrupt: pin A routed to IRQ 18 Region 0: Memory at d0000000 (64-bit, prefetchable) [size=256M] Region 2: Memory at f0100000 (64-bit, non-prefetchable) [size=64K] Region 4: I/O ports at 9000 [size=256] Region 5: Memory at f0000000 (32-bit, non-prefetchable) [size=1M] Expansion ROM at <unassigned> [disabled] Capabilities:  Power Management version 2 Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-) Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME- Capabilities:  MSI: Enable- Count=1/1 Maskable- 64bit+ Address: 0000000000000000 Data: 0000 Kernel driver in use: radeon Kernel modules: radeon
GRUB_CMDLINE_LINUX="nomodeset" in /etc/default/grub seems to have fixed it in both Ubuntu and xubuntu-desktop. I will test it for a day or so to see if the problems recur and then post more detail with some links to an explanation.