temporary IIS .NET assembly randomly deleted/missing

I am hosting a WCF service in IIS. Randomly lately I have been getting an error that takes down the service:

error pic http://img543.imageshack.us/img543/7579/errorp.png

The assembly it is looking for is located in the C:\Windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files folder. Im thinking an improper app pool shut down would cause this, but I am not s开发者_运维技巧ure. The server is a Win2003 server.

I had the same issue a while back. I never nailed down the cause, but with changes and framework upgrades it went away. Here is a thread on the issue.