Some of you may experienced this problem in Media Player Classic...
'Media Player Classic - Home Cinema could not render some of the pins in the graph, you may not have the needed codecs or filters installed on the system......'
Here is the solution that you may try, which I found it from the other site.
1. Download the Binary Codec Package(Windows x86 20071007)
2. Extract these files from the .zip archive:
cook.dll, drv33260.dll, drv43260.dll, pncrt.dll, sipr3260.dll
3. Copy&Paste the above files into folder: C:\Windows
DONE! Replay your RMVB and enjoy! =]