Visual Studio 2010 kills (there is no other word) data in one of the arguments of the function in the unsafe block. What could cause this error? The following message shows
Check to see if you have a Debuggable attribute in your AssemblyInfo file. If there is, remove it and rebuild your solution to see if the local variables become available.
My debuggable attribute was set to: DebuggableAttribute.DebuggingModes.IgnoreSymbolStoreSequencePoints which according to this MSDN article tells the JIT compiler to use optimizations. I removed this line from my AssemblyInfo.cs file and the local variables were available.