Something on Vista turned certain files to _OLD

Hello. I had just gotten Vista home premium x32 in september, with my computer. About two months later, the files that aren't in my c:/ drive have been turned into "Windows Shell Commor" files.

They are still regular files, and can be acessed using a certain program. For example, a movie or video named "movie.wmv_old" can be played by changing the format to Windows Media Player, but many other files, like installers, cannot.

Is this a virus from a certain file that i have downloaded, or am I not alone with this problem.

My Computer