I have now finalized a complete walk through on how to properly install DNN to the root of the hosting account for any Windows based Godaddy.com hosting account.  I have tested it and found it to be working very well so far so believe that this may solve your issues if you are willing to do a fresh installation, otherwise you can take a look over it to see if there is anything that you can take from it to help you out.  You can check it out free, no membership required, but membership is required to post any questions issues, but membership is also free so still no cost anyways no matter which way you go.

http://spencerteck.com/Forums/tabid/54/forumid/6/threadid/12/scope/posts/Default.aspx

I actually had performed an update on DNN and unfortunately my register/login buttons had broken at that time.  It does work now, which I know for sure since other users have registered since your attempt (I think you may have also registered now).  I have actually only had a couple of users so far that have been unsuccessful in getting DNN to run from the root in a Godaddy.com hosting account.  In both cases the errors they were getting just did not quite seem to make sense but started out with issues with the assemblies which ended up not being something that I could assist them with.  I have had others install to the root of a Godaddy.com hosting account without issues using the walkthrough and have also walked through it again a couple of times myself with no issues so I know it is working, but it seems that there is at least a couple of servers at Godaddy.com that just won't corporate ;-)