For weeks I have had problems with very sluggish screen response. Typing in web browser windows caused words to run together and the extra spaces to appear after the merged words. Running MS solitaire, dragging a card left a permanent trail of card images. I used solitaire as a debugging tool. I have played a LOT of solitaire over the last week or so. This only seemed to happen when FireFox was running (well obviously to type in web screens). I went through and disabled each piece of FF add-on software in turn to determine what would clean up the problem. I ran out of FF items and started on OS installations. Disabling Prevx fixed it. Completely. System has now returned to responsive (i.e., snappy) screen response. No delay between keystroke/click and screen display. Something be bad broke. Win XP 32 bit current, FF 3.5.4, Zone Alarm, SB resident, Spyware Guard.