Hi,
Are you sure you have a K-lite MEGA codec pack? What you lack is the Real Alternative codec.
There are four versions of the K-Lite Codec Pack:
1. Standard contains everything you need to play all the most commonly used audio and video formats. This package should be enough for the average user.
2. Full..
3. Corporate Edition...
4. Mega is the same as the Full version PLUS Real Alternative.
I had the same problem as yours but I then installed the Mega version of K-lite and now RMVB files play without a hitch.
U can get the codecs with detailed info here:
http://www.codecguide.com/about_kl.htm
