x-windows starts sucking cpu
Every once in a while, my xwindows stops functioning and starts using most of the cpu power. I know this because I can ssh in from another computer (slowly) and top shows me. Killing x terminates the session and xdm starts again and everything is good again.
Does anyone know how to narrow down what is sucking the life out of my computer? X works fine normally, just once in a while it goes south.

links again
New centre for dementia sufferers The struggle for learning support Traditional X rays to go digital Nine die in fresh Assam violence Warning over poor mortgage advice Medical emergency scheme starts Decision due on laser gateway New BA pension details revealed Far right MEPs set to join forces Quiz star describes £250,000 win BBC soap suspends obscene actor Road crash woman dies in hospital The struggle for learning support Monkey Manuel stolen from caravan Plan for new school presses ahead Trident demo politicians arrested Woman was wrongly labelled abuser Russia oil row hits Europe supply New life for pioneer cycle track Enjoy adventures plea by widow