Windows 7 changes font size?

I Recently got a new laptop, with Windows 7 installed. I find that hovering the cursor does some strange things at times. Currently, two of the sites I visit (Y!A being one of them) now have very small fonts, and I can't figure out how to change the font size back to normal. Can anyone give advice on this issue?
Update: @ JT: It's not a global problem, only two sites are affected. I don't want to enlarge font sizes on every site; I just want to restore normal size to Y!A and the Christian discussion forum that I moderate.
Update 2: @ LDP: THANK YOU! Problem solved. Ctrl 0 did the trick.
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