unity crashes when using [alt][tab]

Probably a dup of bug #691653 "Compiz crashes when using alt-tab (the radeon driver kills it)"

Or a dup of bug #684745 "Alt-tab causes compiz assert failure: compiz: main/mipmap.c:43: bytes_per_pixel: Assertion `b >= 0' failed." which already has eight duplicates.

This has been fixed for a while in Unity.

This has now reappeared in 11.10 64 bit.

Happens to me several times a day. Is there anything I can do to help finding the problem ?

When it happens, unity is gone, all open windows are without borders and are not "clickable". Only workaround I know is to switch to the console (ctrl-alt-f1), login with my user and start unity again. Then I can switch back (ctrl-alt-f7) and continue working.

Some details:
$ uname -a
Linux lnz357 3.0.0-15-generic #26-Ubuntu SMP Fri Jan 20 17:23:00 UTC 2012 x86_64
$ lspci
00:00.0 Host bridge: Intel Corporation Core Processor DRAM Controller (rev 02)
00:01.0 PCI bridge: Intel Corporation Core Processor PCI Express x16 Root Port (rev 02)
00:16.0 Communication controller: Intel Corporation 5 Series/3400 Series Chipset HECI Controller (rev 06)
00:16.2 IDE interface: Intel Corporation 5 Series/3400 Series Chipset PT IDER Controller (rev 06)
00:16.3 Serial controller: Intel Corporation 5 Series/3400 Series Chipset KT Controller (rev 06)
00:19.0 Ethernet controller: Intel Corporation 82578DM Gigabit Network Connection (rev 05)
00:1a.0 USB Controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 05)
00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset High Definition Audio (rev 05)
00:1c.0 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 1 (rev 05)
00:1c.4 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI Express Root Port 5 (rev 05)
00:1d.0 USB Controller: Intel Corporation 5 Series/3400 Series Chipset USB2 Enhanced Host Controller (rev 05)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev a5)
00:1f.0 ISA bridge: Intel Corporation 5 Series Chipset LPC Interface Controller (rev 05)
00:1f.2 RAID bus controller: Intel Corporation 82801 SATA RAID Controller (rev 05)
00:1f.3 SMBus: Intel Corporation 5 Series/3400 Series Chipset SMBus Controller (rev 05)
01:00.0 VGA compatible controller: ATI Technologies Inc RV710 [Radeon HD 4550]
3f:00.0 Host bridge: Intel Corporation Core Processor QuickPath Architecture Generic Non-core Registers (rev 02)
3f:00.1 Host bridge: Intel Corporation Core Processor QuickPath Architecture System Address Decoder (rev 02)
3f:02.0 Host bridge: Intel Corporation Core Processor QPI Link 0 (rev 02)
3f:02.1 Host bridge: Intel Corporation Core Processor QPI Physical 0 (rev 02)
3f:02.2 Host bridge: Intel Corporation Core Processor Reserved (rev 02)
3f:02.3 Host bridge: Intel Corporation Core Processor Reserved (rev 02)

This bug cannot be Invalid. It still happens for me in Ubuntu 11.10.

After few minutes of work in Unity when I hit Alt-Tab, unity crashes and all windows are without borders. I am using standard Catalyst video drivers.

Yeah, it's happening to me frequently in Ubuntu 11.10 on a MacBook 4,1.

for oneiric see bug 916879

Happening for me too.

Ubuntu 11.10
Thinkpad with nVidia GeForce 9300M GS

Found another workaround which is to select Unity 2D from the login screen until it's fixed.

Me as well. Screen flashes and I'm guessing unity crashes when using alt-tab.

Ubuntu 11.10
Mobile Intel(R) 965 Express Chipset Family
(checked and this card is supposed to be supported).

Hi, there are two reports on the issue. I'm consolidating them and migrating everything over to the other one (even though it was reported later) as it has backtraces and a more clear description.

Thanks!