Unhandled exception returns junk characters instead of error

In my ASP.NET (3.5) application, I don't have global exception handling, and if an unhandled exception is thrown, instead of getting the standard yellow ASP.NET error, I'm getting a bunch of junk characters (fairly long, and different each time) - stuff like:

y6����h����H'��:���ղ�>�Ey�裟��Y��>:�O���b�>ZV�"+壦�A�(?��Ӫ��G�2��=�%�w�@}

Obviously, I'll fix this by putting the correct exception handling in the app, but do you have any idea what this could be? For debugging purposes, it's sometimes nice to see the yellow exception screen.

I see this both in my dev environment (Windows 7) and on the server (I think it's Windows Server 2003 with IIS6, but I'm not sure).

It happens on all browsers - if I view source, the junk characters are actually in the source.

Thanks

This could be a character encoding issue.

That sounds like some sort of memory corruption. Have you tried debugging by stepping through the code execution via Visual Studio on your dev machine? Debugging through YSODs alone can sometimes make it hard to find the exact cause of the error.