Recently, within the past couple of weeks or so, whenever I play a video (avi, wmv, mp4) in Media Player (or VLC) the the video and audio is out of sync. It's not out by much, but it is clearly noticeable. Oddly, if I play them in Media Player Classic they appear to be in sync (or as near as).
I know for a fact that these videos used to play fine, so it's not a problem with the files themselves. I haven't knowingly downloaded any codecs or anything else that may have caused this, and I've scanned extensively for viruses and spyware.
I want to reiterate that up until a while ago the videos played fine, so it's not a spec problem. For information, I'm running Microsoft Windows 7 Ultimate 64-bit on a G840 2.80GHz dual core with 8Gb of RAM.
Internet searches have so far turned up nothing. I'm tempted to fish out my old XP machine and test the videos on there, but in the meantime, any help or suggestions would be gratefully received. Many thanks.