Screen wont resize!

Screen wont resize!

Turned my computer on today and the screen looks too small.
It's as if my monitor is too small for the size of the image I should be seeing. I try to change resolution down to 1024x768 or 800x600 and that only makes it worse cause
I then see even less of the total screen, i.e. eveything looks REAL BIG. It's as is the screen wont resize.

It's a 17" lcd flat panel that I'm using with XP!

It was playing fine last time I was on.

Any thoughts?

thanks chris