Application crashes on trying CreateInstance

Question

My Application is created in Vc++ and from the exe I try to load a Excel plugin which is created in C# . I communicate with Excel Plugin by using CreateInstance . But after doing 2 or 3 communications . Create Instance crashes on checking the Event Viewer I am getting these entries

1) .NET Runtime version 2.0.50727.4206 - Fatal Execution Engine Error (693D7B6E) (80131506)

2) Faulting application ExcelCommunicator.exe, version 6.6.0.0, time stamp 0x4caab5d6, faulting module mscorwks.dll, version 2.0.50727.4206, time stamp 0x4bf4c6a7, exception code 0xc0000005, fault offset 0x0006c3d1, process id 0x%9, application start time 0x%10.

Can some one help me solving this issue