PInvoke problem

Question

I am calling GetStartupInfo API using PInvoke from a C# dll. An exception is thrown when a C++ exe loads this C# dll and calls this PInvoke function. "Invalid Address specified to RtlFreeHeap ( 130000, 20d10 )" This exception was not thrown when I replaced the C# dll with an exe(using the same PInvoke format). Can anyone throw some light on this problem? thanks, Rishi