Uninstalling C++ runtime libariess is not a good idea.
doing so may break other programs like antivirus detection.
A good solution is to use Metafox (it can be downloaded from my tools page) to create MKV's from those rmvb files.
It cant get any easier to use. Once installed, there is an icon on your desktop. All you have to do is drag n drop the rmvb, or even a whole folder of rmvb's to the Metafox desktop icon and it willl instantly create MKV's using the original audio/video contents of the rmvb.