What dose "database table is locked" mean?

[Mav12]

Im trying to figure out why my custom civ keeps crashing, and the databse log is spouting database table is locked for various sections of code (and by spout I mean repeating the same line over and over untill the game decides to CTD)

also for some reason the gamecore log is saying null for finding civilizations, dispite them being in the slection screen and eveything

EDIT: Ive solved the issues w/ my custom civ, but Im still curious as to what this means