pinvokestackimbalance -- how can I fix this or turn it off?

First, understand that the code is wrong (and always has been). The "pInvokeStackImbalance" is not an exception per se, but a managed debugging assistant. It was off by default in VS2008, but a lot of people did not turn it on, so it's on by default in VS2010. The MDA does not run in Release mode, so it won't trigger if you build for release.

In your case, the calling convention is incorrect. DllImport defaults to CallingConvention.WinApi, which is identical to CallingConvention.StdCall for x86 desktop code. It should be CallingConvention.Cdecl.

This can be done by editing the line [DllImport("ImageOperations.dll")] to be:

[DllImport("ImageOperations.dll", CallingConvention = CallingConvention.Cdecl)]

For more information, see this MSDN reference

To turn it off:

1. CTRL + ALT + E
2. Under "Managed Debugging Assistants" uncheck PInvokeStackImbalance.