After giving up on my last attempt at upgrading my test website to DNN 4.5.5, I restored my database and website from backups.  This week, I tried again, and now I'm seeing a large number of "Application Shutting Down Shutdown Details: The AppDomain shut down because of the hosting environment." messages in the log.

The shutdowns appear to be because of the website being idle, yet the shutdowns are very frequent. It does not seem to affect the browsability of the site, other than an occasional increased delay in loading some pages.

Does anyone have any idea on how to prevent these shutdowns from occuring?

I am having the same problem, and we want to avoid the recycle if possible.  What can we do to avoid this?  Where is the default 20 minute setting you refer to?  Is there any sort of stay-alive program that would help with this problem?

Thanks - Andy Ziegele