Comment #73 on issue 975 by ngrilly: 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 am using Ubuntu 10.04 and I confirm that installing the package xul-ext-gears solves the issue. Thanks to that package, I have Google Gears working with Firefox 3.6.
