what you will want to do is get rid of all the crap players and stick to one you like,

get gspot (it's a program that looks at a file and tells you wich codec you need and if you have the respective codec or not_

also try to search for a codec pack that has most popular codecs in one, i used to like k-lite codecpack, but there are more out there.

running to much different players doesn't help you since in my experience it's hard to have all the codecs apply to all of them, i just use windows media player 10 with all the codecs i need and have not a single file i can't run as of yet (except corrupt files and maybe realplayer files but i never use those, and if i want to i can probably play those aswell, just get the right codec)