No offence but PHPBB Sucks, I've had to reinstall it 10times and I always get the same dam problem, and ive done everything read about 100pages and nothing, so sadly phpbb has lost a user oh well.. just gonna have to goto invision
All I can tell you is "good luck". phpBB is by far better and easier to use than any other forum software available, believe me, I've tried many of them.
I'd also like to point out that you didn't even bother to tell us what the error that you've gotten 100 times is. For all you know, the problem could have nothing to do with phpBB. It can be a server or database issue for example.
If you can't get phpBB to work, I doubt you'll have better luck with anything else. I'm sure we'll be seeing you soon