White box in the middle of the LCD screen

I am running a Sony Vaio, Pentium 4, OS XP Home sp3. I have this annoying "white box" that sits on my desktop. I can cover it with other programs, internet, etc. There is also an "empty" box on the taskbar that seems to go with it but has no action when I try to delete, etc. I can work around it but it does get annoying since I can't see all of my desktop icons. If you have any ideas, i would appreciate it!