Weak sound from Divx movies

[mach]

I have a kind of weird problem when i play some of my Divx movies on my pc. I recently formated my HD and after reinstalling the whole bunch of programs inclusive Divx4 and WMP especially the audio i get out of the movies plays quiet slow, but the picture quality is ok but again kind of slow. This problem didnt exist before I formatted the HD.
Is it necessary to install a new kind of codec to solve this? what do you suggest?

[pacmania_2001]

Try defragging your hard drive. That causes quite a lot of slowing down. Also when watching movies shut down all other programs that arent neccessary using ctrl+alt+del. Also make sure that you are using up to date drivers for your video and sound cards not just standard windows ones. Also install the latest version of Direct X if you havent already.