I Moved To Another Server, Went From 3.5.6 to 3.6.4, Created Registration problem

I didn't see this problem before but I need help figuring this out so here goes:

When I signed up with vBulletin, I had tons of problems, among them uploading and whatnot. I was using 3.5.6 because I didn't have enough MySQL or PHP space while using GoDaddy. Because I had everything uploaded in the original install incorrect, the board eventually crashed, which I didn't expect it to go smoothly and am very suprised it didn't crash sooner but anyhoo, a friend moved me from GoDaddy to his server and upgraded me to 3.6.4. Of course I lost everything and had to start from scratch. My members had to re-register but for some, when they tried to the system told them that the screen name already exists but it's not in my new username database. I asked some of them to click the link when it asks "forgotten password" and this is what they're getting:

The following errors occurred during your registration:
That username is already in use. If you are (membername) and you have forgotten your password, click here.
Invalid Referrer Specified

Is there a way for me to retrieve the old log ons and if not, how do I get past this problem with the registration of the members of the previous installation?

First of all, welcome to vB-FAQ. Reguarding your problem, two things come to mind.

When you moved to your friends server did you change to domain or path at all? For instance were your forums at myforum.com and you changed it to myforum.com/forum? I'm thinking it's a problem with the domain name listed in your ACP.

Log on to your admin control panel (ACP) and double check the domain and path you have listed under vBulletin Options.

Secondly it doesn't sound like you completely lost everything. Did your friend download the database from GoDaddy and import it on his server?

Second - do you have a backup from godaddy? Check with them - you should be able to get one and go back to how it was. THEN - you can upgrade again, properly.

Thank you for the welcome and yes he did change the domain path from myforums/forums/index.php because when I uploaded it like this and asked the main vBulletin.com site if this was correct, I got no response so I proceeded and the board worked like this for about 3 weeks then completely crashed...going back the old way and with GoDaddy is not an option...I'm going to have my friend double check the paths...

Thanks for the help...this site was recommended to me by another poster and the quick help is appreciated...