Windows Media Player Trouble

Lately my Windows Media Player has gotten picky. Used to be I could play all my .wmv files no problem, even jumping to whatever part I liked best.

For whatever reason, since last week, any newly converted wmv files don't play on WMP. It pretty much stares blankly, like it can't process the file. I've never had this problem before even though since getting this HP laptop this spring, I've taken a liking to keeping it on standby when not using it.

I'm still able to play mp4 files, but the irritating thing is I can't skip to any part of it. It starts from 0:00 and goes from there. Not fond of sitting through boring opening anime themes!

I'm open to another video player, but would like suggestions for trying to fix WMP--assuming I fix it, suppose it's better not to leave it running when I put the laptop in standby? Thanks!