Re: getting an installation error but the bb has been running for a week
So, what does your bb-config.php look like?
Also, this happened to me recently due to something completely stupid that I did. I was trying to solve a connection problem (connecting Navicat to the database through an SSH tunnel) and I reset my MySQL password with phpMyAdmin to be certain I was using a valid password. I forget that I had also used that account for the database connection in bb-config.php as well. So, I noticed later that bbPress stopped working with that same exact error.
It would be worthwhile to try connecting to the database with the details that are currently in the bb-config.php to see if the connection details still work.