The requested resource is in use
The error "The requested resource is in use" is fairly common in Windows. If you're getting this with ASP calls, it usually means something is not up to date.
This really isn't an error you can "cause" in ASP by writing bad code. It means that something in Windows isn't maintaining its coherence properly, the locking and unlocking of access to resources. You don't do that in ASP.
Be sure to run through all the updates available for Windows, IIS and ASP. Sometimes it helps to make sure ISAPI caching is on. But really, if you are fully up to date, you shouldn't be getting this kind of an error.
ASP Error Listing and Solutions