Need help with Windows Vista & a .dll file

[RadarScope1]

OK, looking for some guidance from RB members who are a lot smarter than I am....

So a few days ago I tried to start Firefox (my primary browser) and got an error message saying it would not start because of the dwmapi.dll file. I tried re-installing FF but got no change. I pulled up another browser and a quick search showed that many others who've had the problem went and turned "off" the dll file. So I changed my admin rights and added ".off" to the file name.

Well, it didn't solve the problem, and I wasn't able to change it back, even though my admin rights were the same.

A day later I come to find that Vista has restarted on its own (as it does every so often for dumb reason) and now I can't log into Windows at all. I tried to reboot to safe mode, but I'm just getting a black screen with the words "safe mode" and it doesn't look like I have many options available there.

I know shouldn't have messed with the damn file before trying something else that was simpler. But what can I do now? I'm thinking a this point I should maybe re-install Windows entirely. Is there any risk to the stuff on my HDD if I do that?

EDIT: Yes, I've been Googling this stuff but I just don't seem to be coming up with any real answers.

[gtmtnbiker]

What is the exact error message you're getting regarding the *.dll?

[RadarScope1]

OK, I'm back to normal. I couldn't find the proper way to diagnose and fix in safe mode but I've done it now and restored back to my settings of a week ago. I'm just an idiot for dinking around in the dll files.