Seems likely that there are multiple issues being encountered here, but I suspect that if you have Intel graphics and see 100% CPU usage by Xorg you may be encountering bug 599017. If so the frequency of the hangs probably diminishes in maverick and disappears completely in natty. There are some test kernels posted on that bug for lucid (see comment #34) if anyone wants to give them a try.
Seems likely that there are multiple issues being encountered here, but I suspect that if you have Intel graphics and see 100% CPU usage by Xorg you may be encountering bug 599017. If so the frequency of the hangs probably diminishes in maverick and disappears completely in natty. There are some test kernels posted on that bug for lucid (see comment #34) if anyone wants to give them a try.