Run the "sanity check" utility (./sanitycheck.cgi in the Bugzilla_home directory) from your web browser to see! If it finishes without errors, you're probably OK. If it doesn't come back OK (i.e. any red letters), there are certain things Bugzilla can recover from and certain things it can't. If it can't auto-recover, I hope you're familiar with mysqladmin commands or have installed another way to manage your database. Sanity Check, although it is a good basic check on your database integrity, by no means is a substitute for competent database administration and avoiding deletion of data. It is not exhaustive, and was created to do a basic check for the most common problems in Bugzilla databases.