How do i figure out display issues problem?

My computer went to sleep, and when i turned it back on the display was as if it was magnified and was larger. I went to screen resolution to see if this was the problem and none of that changed it, it would only make the screen font/images larger. Is this a display driver issue? I have ATI Radeon 4200HD so i went and downloaded an update for this thinking it might work, which it did not. Can anyone help me in fixing this problem, or what caused it? Thank you.

Thank you for the reply. I played around with stuff last night again trying to fix it, and i realized for some reason when i goto screen resolution, i could not get my montor to be recognized. My monitor (Samsung syncmaster) supports 1920 x 1080 which is what i am used to, however it would only show Generic VGA monitor with the highest being somewhere in the 1600 x XX range. Before i try what you replied with, does this change anything in what the problem could be?

OK i will check the DPI now.

I am not sure on the connections as they are just the basic ones that came with the monitor to the desktop, so i guess VGA? I unhooked and rehooked the connections last night also to make sure nothing was loose.

Yes i updated the AMD drivers after the problem occurred last night.

For some reason i moved the tower back and forth and after i did this, the correct monitor was found on the device monitor. Its reading the 1920 x 1080 resolution currently, however the font and sizes are off from what they were. Clearly shaking the tower cannot be a fix to this problem. Could it mean the video card is loose or maybe overheated to some extent and needs to be replaced?

Not sure how but i believe i got everything back fine for now. If it occurs again i will be back. Thanks for all your help Brink. Much appreciated.

Well im back as that only lasted a week. Like i said it worked fine, or if i turned it on and it didnt recognize the correct monitor hitting detect on screen resolution usually found it. I also uninstalled and reinstalled the video card driver which fixed it once but now neither of those seems to work and back to square one.

The video card is approx less then 3 years ago, does it need to be replaced? Could it mean it overheated? Im not very computer savvy though i fully believe the video card to be the problem. Any thoughts? Thanks.