XP Home SP3
After some time of use - perhaps days - system stops responding to mouse clicks on the START button; stops responding to CTL-ALT-DEL but will bring up task manager from a right click in the task bar.
Only a reboot seems to fix this.
It just started happening in the last few weeks and doesn't happen all that often.
Yet, it's irritating and inconvenient.
I'm using Kavoom KM but I don't think that's the problem because the other mouse functions work OK and I can turn off Kavoom KM and the problem remains.