algorithmic modeling for Rhino
Have you tried re-installing grasshopper!
That's very odd. It sounds like the problem is caused by an attempt to compile the code, but it's hard to be certain about this (if you create a new VB script component, no code is compiled yet). Which .NET framework do you have installed (if you can find out)? You might try (re)installing .NET 3.5, which is a free download from Microsoft.
Grasshopper on Rhino4 needs .NET 3.5, grasshopper on Rhino5 needs .NET 4.0
Rhino5 enforces .NET 4.0, but Rhino4 only enforces .NET 2.0, so there can be a problem with Grasshopper on Rhino4.
Can I revive this thread to ask the same question? VB and C# "edit source" crashes both GH and Rhino with no warning. I'm running GH 9.0062 and .NET 4.5. Any guesses?