Comment 28 for bug 150109

Hardy Alpha 2 behaves as Alpha 1 did. I'll work through the wiki page
https://wiki.ubuntu.com/X/Debugging#head-0b6e9c6b60fa07cda4013a1c51239f1c14c4f89d

Disable Compiz (change Appearance > Effects to none):
No change - C+A+F1 then C+A+F7 to recover.

Disable all power management (how? What do you mean by this?)

Log out of X, and log into the console, and try suspend/resume (or hibernate, or whatever) from there
Again, I don't know the command to suspend from the commandline, but I am fairly confident that it is X because I can C+A+F-key and fix it.

Switch virtual consoles and back (alt-ctrl-f1, alt-ctrl-f7 or f8 or f9)
As above, this fixes the issue.

If laptop, close lid and reopen
Using the lid-close button hangs my laptop Bug #138256

Attach another external monitor
Bug #156062 - I can no longer use an attached monitor.

Edit /etc/default/acpi-support - I will save this comment now in case I lose it and then continue testing.