Cant watch videos - BIOS Blowup aftermath - DONT muck with BIOS

Before i say anything let me offer this advice:
DONT Fiddle with BIOS settings if you dont know what you're doing (like me big noob).

So there i was, bored one night waiting for EOTN to come out. So i fiddle with my BIOS. I put DRAM performance on "Ultra Fast" and BAM! No more computer.

It took me a day to find a Windows XP CD and a keyboard which had an "Any Key" on it ($6 USB keyboard didnt have one).

Anyway, the problem was that i "Corrupted System32". The Windows repair feature "chkdsk /R" worked a treat and i was back online again. Everything was back to normal...

Now cleaning up the aftermath:

I cant watch videos.
Everything but a MPEG will not work.
They will play with sound, but no picture. Even my DVD playing programmes have the same problem. Choppy sound and no picture.
I reinstalled Codecs (i think), Windows Media Player AND my 3D card drivers.

Any clues to how i can fix this?

Thanks in advance.

Is formating your computer an option?

The windows repair may work at times but its really not ideal as you can see.

Why didn't you just reset your BIOS to default?

Chances are it crashed because of the incorrect BIOS setting while doing something important and ended up breaking the file system on the Windows partition. If chkdsk couldn't fully repair it you may have to reinstall Windows to get everything working.

I dont really want to format, but reinstalling Windows is an option. I'll do it once i exhaust all other options.

I'll try find some new codecs and see how they go.

Thanks for the help guys, if you can think of anything else please let me know.