Some idiots are now fuckin with their avatars and sigs: a browser can't find them in the cache (on the surfers' computers), so the mySQL-server gets many requests, too many it seems (can be caused by soft-and /or hardware), for linked pics.
So find the morroons responsible and aks a mod to perm-ban them.
Or: there are many hyperlinks to posted pics, while a part of the database is inecassable. Maybe a drive has died, maybe (more likely) someone accidentily erased the shit, whatever, if I hit a page the server gets requests to serv a picture, but the picture is gone.
The software responsible, mySQL, then generates error-messages.
But I'd say: blame the idiots!