>You should never rely on an object to be there because the AppDomain maybe killed for any number of reasons. Most common is code updates on the server, changes to web.config, IIS idle timeouts of Application Pools.

So, the fact that this only happens on one server might then be related to the IIS setting that can be different from one another.

>Your global objects should always be static and run with a static constructor so they can reactivate on the first hit that occurs against them.

Ok, I'll change that one to static and the related changes that might be related to that.