I've upgraded the server to edgy. I no longer experience this problem. (I also changed video card drivers from fglrx to the OSS ones, perhaps that has something to do with it)
I guess this can be closed. -- Screen refresh problem. https://launchpad.net/bugs/57156 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
