What Will said. Also, phpBB installs always give me a 'can't write config.php' error because I always forget to make it writable. The error will provide workaround instructions. If you give config.php 777 permissions just while you do the install you might not get that error. I use my FTP program to change config.php to 644 after install completes.
Another very common install experience is (when) you get partially through an install and it fails for some reason, you will get an error that tells you an auth table already exists. This kb article at phpBB explains three ways to fix it (personally, I use phpMyAdmin and drop (delete) all tables and then rerun the install fresh).
http://www.phpbb.com/kb/article.php?article_id=75
http://www.phpb.com/phpBB is probably your best bet for in-depth troubleshooting. You'll have to learn to use the Search function and sort through a lot of junk, though :-) Every problem I have ever encountered had already been dealt with there (or at least experienced by others) so it's saved my bacon many times.
Good luck.