Cursor Focus / Ghost Alt-Tabs

Im running XP on a new (3 months) dual core Atholon, and I'm having a problem

with my cursor switching focus mid-typing. Sometimes it goes to the text

prompt in another window, sometimes the text just doesn't go anywhere.

Occassionally, as I try to post chat, I will hit enter a couple times, and it

ends up restarting my machine. I'm using a Logitech USB G-15 keyboard, in

case that makes a difference.

A problem, no doubt related, is the sudden alt-tabbing to desktop while Im

playing a full screen game.

Has anyone any clue what might be the problem? I thank you in advance for

any responses.

Zed