Regarding the first error that I posted on this topic and the image I posted. The behavior we are seeing is the web page displaying an exception (as seen in the image I posted in this thread), once that exception is displayed our log file contains an entry relating to the text showing in the first  post of this thread.

Can you please provide us with:
- correct error that you get with full stack trace if possible
The image I've posted on this thread contains the same stack trace information, unfortunately we're not getting back a very detailed stack trace.
- check if you get the same error with the production app on your local environment 
We do not get the same error in dev environment as well as our locally hosted staging environment. This error occurs only in the externally hosted production environment.
- provide us with your production hosting environment specification
I'm unable to provide you with hosting specs right now, but will asap.

Could heavy reliance on the Session be an issue with our web parts and MonoX? I'm thinking no, but though it wise to ask now.

Thanks for all your help on this issue. As it turns out, the issue apparently is due to frequently changing app pools so that storing the session data in-process is not possible and instead we have to use a ASP.NET state server.
At this time I'll mark the thread as answered.

Regards

Ok, get back to us if you find any other issues related to the section we have reviewed. I'm closing this topic so please open another if needed.

Regards