Graceful Exception Handling

hi there. any unhandled exceptions within our ASP.NET project are taken care of
within the Global Application_Error handler. this allows us to check for things
like whether the Session has timed out. we can then redirect the user to an
appropriate friendly error page.

i have just developed our first Atlas page for inclusion within this project. i
notice that Atlas is somehow overriding the exception handling, even in
'Release' mode. so if i force a Session timeout then i am getting a javascript
popup saying "Object Not Set To An Instance Of An Object".

this cryptic popup is no good for my users. if an exception occurs within the
Atlas page then i really want to handle this in C# codebehind like i do my other
pages, for continuitys sake. is there a way i can disable the Atlas exception
handling and warnings and use my existing c# architecture somehow?

Thanks.