Comment #78 on issue 975 by craigster0: FF 3.0.15 said to be incompatible with Gears 0.5.33.0
http://code.google.com/p/gears/issues/detail?id=975
I posted this fix to the Help Forums. You can see it here: http://www.google.com/support/forum/p/Calendar/thread?tid=0a2aba02dfbeb1b4&hl=en&fid=0a2aba02dfbeb1b4000487f0673e718b
