My mouse acts evil during fullscreen games, can someone help?

My mouse temporarily freezes whenever I hold down the shift key in Total Annihilation, temporarily freezes when I hold down shift, ctrl or alt in The Sims Deluxe, and the mouse will freeze when holding down almost any button in Worms 4 Mayhem. Can someone please help me? I am using a Logitech optical mouse, (can’t identify it) and a Microsoft Natural Multimedia Keyboard with Intelitype. I am running Windows XP SP2 on a 2.3ghz Celeron (@#$%!).