I have a similar issue with intrepid while running the upcoming KDE 4.2 release (building from KDE's subversion). If i let the machine sit idle, then X pegs my cpu at 100% but doesn't cause a freeze. Once I move the mouse, the cpu usage goes back down. I've attached the only backtrace that shows up when I attach gdb to X.
I have a similar issue with intrepid while running the upcoming KDE 4.2 release (building from KDE's subversion). If i let the machine sit idle, then X pegs my cpu at 100% but doesn't cause a freeze. Once I move the mouse, the cpu usage goes back down. I've attached the only backtrace that shows up when I attach gdb to X.