I also experienced the same lock-up using a Dell Inspiron 1525, with Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller.
I can reproduce it with Alt+Tab -ing multiple times. Using compiz and the Shift Switcher plugin.
From the posts above and my experiences I would say that this is related to the keyboard input handling code somewhere in the X driver.
I also experienced the same lock-up using a Dell Inspiron 1525, with Intel Corporation Mobile GM965/GL960 Integrated Graphics Controller.
I can reproduce it with Alt+Tab -ing multiple times. Using compiz and the Shift Switcher plugin.
From the posts above and my experiences I would say that this is related to the keyboard input handling code somewhere in the X driver.