Help Needed: Type goes bold strangely

Hi there,
Over the last two days my computer type has gone from normal to bold. This includes the desktop icons type, the bookmarks within Mozilla, the quick launch bar, the task bar, start bar and MSN Messenger and many more programs (I haven't checked every one). I removed this problem the first time by doing a system restore, but this time I don't want to do that again. I have been through control panel and used the accessibility options, which made SOME of the type normal but not all. Is there anything I can do to stop this from happening? Is it a virus? I have run several checks with different programs and found no results. The only thing i can think of is that both times it has happened the last time I was on my PC I unistalled programs? Any help is greatly appreciated.
Thanks