Global data getting reset when running under IIS?

Question

We have a scenario using IIS with an ASP.NET web service written in VB.NET. When a call to the web service is made, the web service calls a native dll (written in C, compiled using VS2010) using platform invoke, which in turn calls into our product API:
VB.NET web service -> native library (p/invoke) -> native API ....
Web service requests are successfully completed and the system runs without problem for hours. A trace of the native API shows it is being called by multiple processes and multiple threads within those processes.
The main native API dll contains a static global variable used to detect whether it is the first time it has been called and run initialization logic if it is. This dll is itself linked to a second dll that contains a global variable used to detect if it is
the first time it has been called.
After some hours the trace shows that the native API is invoked by an existing process but that the initialization logic is being exercised again, even though the global variable was set to indicate not first time and is never reset.  One theory was that
the first process has ended and a new process has started almost instantaneously using the same process ID. However this is not the case as existing thread IDs from the same process are seen to write to the trace again after the first time logic has executed
for the second time, indicating the process has not restarted. The problem occurs regularly.
It is as though the process's global data has been initialized again and malloc'ed memory freed while the processing is still running. Is there any way this is possible when running under IIS?
There is an internal thread which waits on a blocking read of a named pipe (via ReadFile), and when the problem occurs, the ReadFile call ends with ERROR_NO_ACCESS, which appears to indicate the malloc'ed buffer is no longer valid, again implying something
has happened to the memory allocated to the process.

Answer 1

Suggestting you asking it on:
http://forums.iis.net/