Pardon the intrusion, but in one post you mention Constant Guard and Norton. Those are the products offered by Comcast so assume you are a Comcast customer.
ConstantGuard is the generic name of their entire suite of protection software, as well as the name of the Comcast specific programs. The Norton Security Suite Comcast offers is specific to Comcast.
The Norton Toolbar will work with Firefox 17. Check your version of Norton. It should be 126.96.36.199. If you do not have the mosr current version, then run Live Update as many times as needed, rebooting required, until it return no updates.
If you have other issues with ConstantGuard, then I suggest you post them on the COmcast Help Forums, here: »forums.comcast.com/comcastsupport/
As a general rule, when a new version of Firefox is released, do not up-date to it until the Comcast version of Norton is updated if you want the toolbar to function. You'll have to check the Comcast forums for that information.