I found another issue using Atlas the other day. I was using Atlas UpdatePanel around a TreeView and had some java-script functions on the page elsewhere. All was going fine Tuesday evening, then Wednesday morning, I started getting a what appeared to be a java-script error message.
When debugging, I was able to confirm that Atlas was working, I could step through my server code and populate the tree, but when execution was back at the browser, I would get this error pop-up “Unknown Error”.
Also, see my post in this thread: