Well, I'm amazed it took that long, I have to say... how big is the backup file you're using, and is it SQL Backup or native? Are you accessing it over the network, or is it on the local disk?
Did you manage to find out whether you're using a non-clustered index or a clustered one as the comparison key on the particularly large table? As I said before, this can have a huge effect on performance.
As for the timeouts... I'm confused. Especially since it was only on one side, despite the fact they're identical controls!