After 30 min my screen saver kicks in, lately it does not respond when mouse or keyboard is touched, XP 2000 OFFICE, I have TRIED ctl alt delete, and esc, neither works, have to rebootIs the screen saver still running when it locks up or has the screen went blank?  If it has, it is POSSIBLE that either the computer has gone into 'standby' mode or even 'hibernation' mode.  I know I have never had any luck with stanby and my computer never comes back with out REBOOTING.  If that is the case then try disabling it.  If it is not, I suggest first a thourough virus scan, second try a different screen saver.  After that I am at a loss at the moment. Good luck Screen saver is still running, microsft plus, fish in a tank, whatever, I ran virus scans, spy wear, defrag. ETC. I have not tried another screen saver yet, just bugs me that I can't find out why this is happening. Thanks anyway Cagef8 safe mode and chose the last good config or  type msconfig in the run box and chose selective start up.. and losk in the control panel admin tools event log errors..and if not scan for the m$BLASTER worm..