Thanks marto for the reply.

The application is used for batch processing, so the user had 2700 objects (files) to process, and it's the repeated processing of these objects that cause the failure. The user is using windows 7.

I'm almost certain that our code is wrong, but am not sure where to start debugging. Creating a repeatable case is difficult as the objects that the user are using are sensitive. I've tested the app at the high level (process monitor and explorer) and I can't see a file handle leak so I was hoping to do something at the perl level?