running, windows XP if I leave Pc for a while, I come back whilst still online, and cursor has "Frozen" it cannot be moved, control, alt, delete, does nothing, the only way to bring it back is to reboot
Probably the 1st easy test is to change the mouse if you can and see what happens and also use a different USB port ( assuming USB, not wireless). Does the freeze happen at other times if not using browser ?
At time of freezing, check your HDD access light and see if it is on constantly.
Also, once you do your alt, ctrl del wait for a minute of two to see if the task manager finally appears. If it does, go to processes then click the CPU column (twice I think) to put the highest CPU usage process to the top. My theory is that a process (possibly a trojan) is using 100% of your processor time and doing this may help you find out what it is. Best wishes,