This problem was first discovered in this Userlogos thread

The symptoms, as can be seen from the thread, is that although it seems possible to load Fast Dial into Firefox, on Computer reboot Fast Dial does not work and is found to be incompatible.

This problem seems to being caused by Norton

Norton is force installing its own extensions into Firefox without asking the user, and to to enable this process is deleting extensions.rdf on computer bootup.

Norton has not yet come up for a fix to this whole issue.

For greater details of the whole problem please see this excellent thread in the Norton Support Forum here

As can be imagined this behaviour of Norton is very frustrating for fast dial users, as bar trying one of the fixes suggested, it is necessary to reload fast dial after every computer reboot !!