The Lindens have already replied, 19 hours after creating the ticket and minutes after updating, saying they have "run a script" to fix it. I was directed to a low lag sim (Welsh) where I appeared with a default avi. Following their directions I flushed the cache and relogged, then stayed logged in for about 2 hours. I am able to change my looks again and right now everything looks good. Will have to test everything, though.