Ugh. The only reason I'm not furious right now is because I was able to restore all my work from my daily backup.
I see that others have had this problem too.
This is an instant way to turn a loyal and happy customer into an angry ex-customer. You really gotta find this bug and fix it ASAP.
So... I paid for an upgrade, but want to wait until there is fix.
Yes, I did try replacing the ~/LIbrary/Application Settings/BetterTouchTool folder from my backup, but nothing shows up.