Deadlock troubleshooting and resolution:

http://blogs.msdn.com/bartd/archive/2006/09/09/Deadlock-Troubleshooting_2C00_-Part-1.aspx

Note there are 2 additional parts to this blog series.

You can also get a professional on board who could probably resolve the issue in a matter of minutes or hours as opposed to many days like this has been going on.