go onto the blackberry website, change your password, reboot your device and try to change your account settings under the playbook options...it should work
The same thing happened to me (back on 2.0.0.7111)
Setting the PB clock to 2 years into the future unlocked the PB, then I set it back to the current year and all was still OK.
Change your date/time settings and force the date after 2020.
Then reboot your PB.
Then try to connect to app World
If success, change the date back to auto.
That it does, it was similar to the problem I was having. I got it fixed, I had to fix the issue with my BBID first then skip ahead a few yrs and then bring it back.
If you are trying to say I should have did a search before I posted then I suggest you look at the time stamps on the posts. My thread was created a couple of hours before the one you posted.