Desktop Appearance Magnified

Hi there,
When I leave my laptop idle for a few hours (such as after closing the lid
overnight instead of shutting down) the screen looks magnified and distorted.
My clock looks stretched, and the fonts are strange. If I start using
anything it all looks magnified and strange. The only way to stop it is to
restart the computer. Does this sound weird to anyone else? I have no idea
how to fix it. I may just have to add it to the "Vista - impossible to fix"
list.
Thanks
Linnybins