Font corruption?

I *think* I'm posting this in the right place..

A couple of days ago, for no reason I can determine, my system has decided
that most things showing in the Arial font will henceforth be in italics.
This includes many web page documents (such as news articles), a lot of
verbage on AOL screens that displays as regular font on my wifes computer and
my office computer, and several other places.

Any ideas on how to fix this? (The only out-of-the-ordinary thing that has
happened was that I got some 'net framework' error at some point, but can't
recall just what it was.)

Thanks!

- MrBill