Re: Sign up fatal error!
Whether you are upgrading or installing BuddyPress for the first time, the instructions are clear on what to do with the theme files:
Please, always read the instructions before upgrading an old or installing a new copy of BuddyPress. The readme.txt file that comes with BuddyPress is also clear on what to do with the theme files.
As it is quick, simple, and painless, I always manually upgrade or install new BP versions, instead you using automatic update. You have more control over the process.