"PDB does not match image" error in C# VS2010 project

I've run into this issue before when I have another project open that also references the DLL and uses its debug info (PDB). Basically the other project puts a file lock on the PDB in the referenced project and when you compile or debug the referenced project, it quietly fails to generate an up-to-date PDB file.

If this is what is going on, make sure you have no other apps running or instances of VS open that reference your DLL, and then seek out and delete all copies of the PDB from beneath the BIN and OBJ folders, then recompile it.

I hope that helps.