Attempted to read or write protected memory when calling VML functions

Hello,

I build a small C# project that calculate some VML functions:
Abs , Arg, Add, Mult, Cos, Sin
I ran this functions in multi threads - about 3000 threads using .Net threadpool that use only 4 threads.

Sometimes an exception occur : "Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

I attached the project and the exception screenshot.