If you are a U2.com member continuing your membership from the old version of the site to the new one, and are unable to log in to your account - it is totally worth calling FanFire about it (the US and international numbers are on the help page here - http://u2.com/help/index/). I know a couple people here were having trouble contacting the site via e-mail. The issue with my account was that my previous password had a special character in it (like @ # % $ & etc), and the new site doesn't support passwords with special characters... only numbers and letters. It had to be manually reset by FanFire, I couldn't do it from the site myself (which, of course, I didn't know until I called them after attempting to reset the password on my own like, five times).
The person I spoke with mentioned that they've had lots of issues with the new site and people having trouble logging in. They were able to figure out and resolve this for me in just a few minutes, so definitely give them a call if you're locked out!
One perplexing thing about the site for me has always been that half the time, the answers to the questions you have are in Zootopia, but you can't access Zootopia unless you can log in, and if you're having login problems... well. You know.
Hopefully nobody is having trouble, but I thought I'd throw it out there just in case!