I am using FF 3.5.8 and do not see the ZA browser bar. When I right-click the bars it shows the ZA bar as active, and when I un-check it I get this error message:

unload: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsIObserverService.removeObserver]" nsresult: "0x80004005 (NS_ERROR_FAILURE)" location: "JS frame :: chrome://trustchecker/content/trustchecker.js :: anonymous :: line 949" data: no]