I have been tasked with setting up asp.net websites on a windows server 2008 which are all in debug mode

When browsing a website on the server and an error occurs, for example the database connection cannot be open I would expect as per normal to receive the Asp.net Server error page with an error dump

Something like - http://www.codeproject.com/KB/books/1861005040/image091.gif

However, what actually happens is I get random characters on the web page. For example: <?)=????*??2o????v??YK?WuZ,?6[N??f?O??b??@!???u]S??yQ?iN?&e???E???j??1z??x??????o?y????U??M???2d?i?4

This is not the correct or expected behaviour. The event log does however show what has gone wrong.

How do I get the Server Error page to render properly, am I missing something in the servers asp.net setup?