RealMedia files (.rm .rmvb) freeze or play without sound
Media Player Classic is not fully compatible with RealPlayer 11. There are two ways to solve this problem:
Uninstall RealPlayer and install Real Alternative.
Replace the file cook.dll with an older version from RealPlayer 10.5.
You can download cook.dll from:
http://www.down-dll.com/dll/c/cook.dll.zip