I was having a problem and have seen similar reports in the forums of the bitcoin GUI not working on ubuntu 11.04. This is repeatable when using either unity or compiz. Disabling both of those works around the problem.
This workaround (http://svn.wxwidgets.org/viewvc/wx?view=revision&revision=67496
) was submitted recently to the wxwidgets source repository. I maintain a ppa archive of bitcoin packages (https://launchpad.net/~stretch/+archive/bitcoin
), and patching that workaround seems to have fix the unity/compiz problem.
I'm not sure there is much that can be done with the bitcoin source tree to workaround the problem, so this is more of an FYI of the problem and the fix.