I realize that there is already a thread on this topic, but my question wasn't answered quite the way I wanted.

I previously had DivX as my codec. I imported .avi files into Vegas 7 and it played the clip like it would for any other video file. A few days later I obtained a file which was in .rmvb format and because was I desperate to view the file, I went on a rampage and downloaded random codecs (whatever program I had [perhaps codec, too] didn't support that video file). After that, .avi files didn't work in Vegas. It worked fine before, but how come it doesn't now?

Can someone help? I have this video converter, but i's being dumb and I can't seem to work with it. Also, I wish to not convert each raw file before I edit it into a personal video.

As a side note, I'm not so sure if I have the DivX codec still installed as the first new codec I installed requested that I remove DivX. However, I still have two DivX icons on my desktop. DivX Converter and DivX Player.

Help.

How do I make .avi files work again?

Just remove all those codecs (Then re-install only the ones you need, not mega-packs or anything) and re-install Divx, should work.

I went to my control panel then to the programs that I can uninstall and from what I could see, I only have DivX installed. Still, .avi files do not work. :(

Do a System Restore. Pick a date when your system was working ok

@inya1lake: How do I go about doing that? Will it delete any of the other files that I've downloaded and installed after all of this happened?

Unfortunately it will, but you can always undo the System Restore if you don't like the results. If you are using XP and want to try it -
Click Start (bottom left of screen) > Help and Support > Undo changes to your computer with System Restore (under sub heading Pick a Task) > Restore my computer to an earlier time (default) > Next > select a date you want to restore to (Bold Numbers) and >next again.
If you don't like the results follow the above steps again but instead of choosing"Restore my computer to an earlier time" select "Undo my last restoration" which will take you back to where you are now. Hope this helps.

System restore sucks, just delete all the codecs you installed to make that stupid format/file work (Including Divx). Once that's done, restart, then install Divx, everything should be fine afterwards.