Real buggy coding night. I'm in the process of putting together a site for myself when I ran into this problem:

http://forums.microsoft.com/msdn/showpost.aspx?postid=98346&siteid=1

Basically "Failed to generate user instance" and "An attempt to attach...failed".

For "An attempt to attach....failed" I was able to get around this by simply rebooting my development machine. Apparently there is some local cache of files stored on the hard drive that SQL Server Express uses and this was getting out of wack - somehow rebooting the system did the trick for me. It went away, but I was not able to identify exactly what caused the problem; to me this is a bad thing - I really like knowing WHAT happens when something goes wrong.

The "Failed to generate user instance" came from me being remoted into work from home (that'll teach me to work from home). Oh well, I guess I get my site done tomorrow.

Hrmph. :-(