help please!

I have been using LW for quite awhile now and have not really had any major probs with it until recently. I upgraded to 2.7.3 and am running XP Pro and have noticed that every time I move my mouse across the screen, LW goes blank and then will reappear. Is this a common prob and I just haven't looked deep enough to find the answer? I have spent the last couple of hours reading the faq's and posts here at the boards, but have not come across anything. If anyone has an answer for me it would be appreciated.

Thanks in advance