FDF to PDF Server Application Unavailable

I have a custom built CRM that is 99% written in Classic ASP/VBScript. Currently we use a FDF to PDF script that generates a bunch of PDF files (depending on which PDF you are choosing to merge.)

Almost exactly the same time every day, at around 9:30 AM my users can no longer use the function as the error "Server Application Unavailable" appears when they开发者_C百科 try to use the function. The error then may happen randomly or nearly every 2 hours thereafter - but it depends on usage. In order for me to fix this, I have to either restart IIS, or Recycle the App Pool.

The App Pool that the site resides is independent of all other applications on the server.

The script was written in .NET by a 3rd party company and I can post the code here if required.

There is nothing in Event Log, and I'm unable to find any logs or indications as to what the problem may be. Any ideas?

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If your application pool's idle timeout is set to 120 minutes, this could explain this issue appearing every two hours. I have had issues where certain long-running processes idle-out and are shut down by IIS.

EDIT:

I just poked around, and I found this, which looks promising.