In older versions of Window (XP and Server 2003) it might be required to activate ASP.NET 2.0 (This can happen even if Microsoft.net 2.0 is properly installed).

In C:\Windows\Microsoft.NET\Framework\v2.0.50727 run aspnet_regiis -i

This has to be done especially if you start VMEP and get a system error message from ASP.NET version 1.1xxxx.