Comment 5 for bug 56427

Similar on my U5, it's just that X.org won't start.

See Thread from Ubuntu Forums:

http://www.ubuntuforums.org/showthread.php?t=307406

This might be related to

Bug #392312 on bugs.debian.org: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=392312

respectively

Bug #8020 of bugs.freedesktop.org: https://bugs.freedesktop.org/show_bug.cgi?id=8020,

where David S. Miller writes:
"[...] The code in hw/xfree86/os-support/bus/sparcPci.c:simbaCheckBus() is trying to mimmick VGA routing by disabling I/O space responses behind the Simba PCI-PCI controller. [...]"

http://kristof.willen.be/?q=node/689 proposes a workaround, which basically is to get the fixed binaries out of Debian's xserver-xorg-core package and to replace the ubuntu ones in /usr/bin.

Can't help but researching here, I have no clue about programming and package building...

regards

Marc