Comment by ghaff

I managed to corrupt the SQLite database that Lightroom uses last December. Around that time my old Windows system was having some hardware issues (random crashes) which led me to upgrade to a Mac Mini. However, after the upgrade, the problems started reoccurring and eventually Lightroom wouldn't read in the database at all and wouldn't repair it. I suspect that something bad happened during one of the system's random overhear or whatever shutdowns.

As it turned out, I was able to fix the problem by dumping the database and creating a new one. Oddly enough, Adobe's repair function apparently didn't try this fairly straightforward (once you knew to do it) repair process.