PW3 Automatic update to 5.9.2 broken jailbreak?

My PW3, which was successfully jailbroken until yesterday, updated itself to 5.9.2 overnight and now when I try to run my Kindle Launcher I am told "Application Error. The selected application could not be started. Please try again." Restarting the Kindle has made no difference. I must have not set backdoorlock up correctly :(

Any thoughts on what I could try? I don't want to do anything without advice from one of you experts first, in case I make things worse...