Well firstly as i said above, check to make sure that SPNG is configured properly - make sure you have the "open links in your default browser" enabled. Do this by going into
Plus! --> preferences --> Plugins --> Stuffplug --> and enabling the option if its not already enabled. (another way to do this is type in /xspoptions in a conversation window).
If it is already enabled then write down the file associations IE has and the settings with them as a precaution (its always good to do this just incase
). Then change the associations with IE over to firefox!