How to switch back to older version???

Hi, I just updated my Bsplayer to version 1.1 Build 814 and I didn't like it. So I decided to switch back to Build 812. However, when I tried to play my xvid movie in the old version, it crashed. I don't have any problem to play it in the new version though. It's just the old version suddenly doesn't work any more after I have used the new version. There was time that I can have mutiple versions of Bsplayer (before 0.8 I guess) on my hard drive and they can both run properly without any problem. And now I have no clue what's going on! Isn't Bsplayer suppose to be a standalone player and doesn't mess with windows? Do I need to uninstall the new version some how in order to get my old version work again? By the way, I use the zip version all the time, and I have no idea how to fix the problem.

So, basically, the situation is this:
I have unzipped both version (812 and 814) into their own folder.
The old version (812) was working faultlessly in the past until the new version.
I ran the new version and it also run faultlessly but I don't like the image quality.
I ran back to the old version, but now whenever I play the movie files, it crashed. (Send error report window pop up immediately)
Then I go back and run the new version, and the new version runs without any problem.

So there must be something wrong in the windows registry but I don't know where to find it!!! Anyway, can anyone help me please! I really want to use the old one. :(