I did have Google Toolbar but it is disabled now and add-ons are the usual Java, Flash etc. and the only odd one would be IESpell but this problem started before I installed that.
I may have to make FF my default although I prefer IE for many things.
I've redone some of my more heavily used desktop shortcuts to open in Firefox anyway, so I'll see how that goes.
This is all going to self-destruct anyway in January I hear, so not too worried.