This also affected me with other extensions and I didn't really make much headway with my bug report. However once you upgrade and recreate preferences, they work from that point forward.
I had problems with the following extensions: User CSS, Ninjakit & Better Facebook where it was causing the same LocalStorage corruption.
You can read up on my conclusions here:
Webkit Bug Report
Last edited by Kevin M. Dean; 10/03/11 06:07 PM.
