DLL Exported name mismatch in crash stack trace

have been observing a weired crash in our dll developed (compiled) using microsoft visual studio. This is a non-MFC DLL which uses def file export mechanism. The client program which uses this DLL is multi-threaded and making calls to exported methods.
There is a method ABC() which is exposed through DLL but which we never implemented (but has basic skeleton ready). This client DLL which which is taking care of RPC communication to our server crashes randomly. Seldom it crashes but each time the crash is reported with a method name mismatch in it.
Like the microsoft even window always show a crash in ABC() which does not have any implementation and is never called either from client program or through any other methods within that DLL.

We used windebugger and even tools like appsight to get releavent information about the crash but the stack trace always shows the method name mismatch.

One good result we got with appsight was it atleast shows the caller method of ABC() which is from the statically linked modules of DLL project.

Any clues, guesses, guidelines on debugging this issue further will be HELPFUL.

Thanks in advance, I hope I will get good replies in this discussion forums as it did not help me to put this question in so called POPULAR techforums.
Thanks
STappe