audio and video imported runs faster than original

When I download video or import video from dv camcorder
or download mp3's they al play faster than original. I
reinstalled all video and audeo codex files but this
didn't help but slightly made my problem worse. eg. play
12 seconds of video in 10 sec accual time, same as the
audio.
Thus sounding like the chipmunks, almost but not quite.

I reinstalled windows as well as a last resort but the
problem is still aparent

pass this on if you know someone that could help