If you ever hit the error below the first thing to check is a endless loop or a recurring call between methods. This happen in a site I was running in localhost when an exception was raise, and email was sent, that email failed raise the exception handler and attempted to email it, then on an on...

A process serving application pool suffered a fatal communication error with the Windows Process Activation Service. The process id was 5388. The data field contains the error number. A process serving application pool suffered a fatal communication error with the Windows Process Activation Service. The process id was 4228. The data field contains the error number.