Ok, so this is one of the strangest issues I've run into yet.
Every so often, the text in Firefox gets garbled or bolded in seemingly random locations. In some cases, I actually have to place my mouse over the problematic text before it will return to normal (scrolling doesn't generally affect it). It seems to happen when a page is loaded for the first time or when something on the page changes (gets re-loaded, etc).
I've also seen similar problems in Visual Studio 2010 as I'm making changes to the files, so it doesn't appear to be Firefox specific. It looks like the text from one location in the page gets overlayed onto another location in the page, to the detriment of the display (see attached files). The last screenshot was just taken as I was composing a message on SuperUser (which has not been responded to at all, which makes me wonder a little).
What could be malfunctioning if this is not a virus? How can I fix it? I'm starting to become suspicious that this is not a virus.
If it is a virus, what have I not done (see below for what I have tried) that I could do to clean it? Note that I do not want to do a clean install if at all possible.
What I have tried thus far:
I have tried to adjust the fonts using ClearType- no change. I tried to re-install some of the basic fonts such as Arial & Tahoma, but no improvement (I couldn't find the rest of them- some help for that would be nice). It started about a week ago or so- I'm wondering about the possibility of a virus. However, Avast! antivirus, BitDefender, Spybot, and SuperAntiSpyware pretty much give it a clean bill of health. The only exception is that several of those found the mouse driver for my SwitchMouse and claimed it was a trojan. It has now been cleaned off (I'll bet it was a false positive, but I'll play along). I have also tried a BitDefender CD boot scan- found nothing. I have looked through the Process Manager and looked up nigh-near everything in running in there- nothing obviously wrong.
The only mildly suspicious thing I can think of that happened at the same time as all this is that I downloaded and installed DVDDecrypter and DVDShrink for copying a DVD that my father created (no copyright issues here). Both programs have now been uninstalled.