I suppose I'm left with uninstalling and reinstalling to see if that will alleviate the situation.
That's the easiest way, if it works. Typically, such process works in 1-2% of any issue. There is an outside chance that a new profile would work, and since it affects only Firefox, I have some problem placing it in the driver's camp. Are you using Seamonkey? That could be the tiebreaker.
UserAgent: Mozilla/5.0 (Windows NT 5.1; rv:11.0) Gecko/20120312 Firefox/11.0 SeaMonkey/2.8
A minority may be right, and a majority is always wrong
~ Henrik Ibsen
WinXP, SP3, 512 MB, SM2.17.1, FF21, TB17.O.5, IE8.0, Google Chrome 26, Ghostwall , Kingsoft5.6, JRE1.7_21.