Strange problem...

While Limewire is running, if I try to open certain folders or play movies with Media Player my display changes. The only way I can think to describe it is it looks like my monitor zooms in about 200%. I can't see all of my desktop and I can't navigate properly in Windows. I have to restart my computer to fix it. Any suggestions?

Pentium III 933 mhz
512 MB RAM
Samsung Syncmaster 912n LCD display
Nvidia Geforce 4 vid card