To Tom and Edwards, the line of code you commented out should only come into play if the check for useSB is true. This tells me that either this variable is mistakenly holding a true value, or the code that is setting this value could potentially have an error.
To Tom, please post back and confirm what you have specified in your settings tab for this in the admin area, this could be the clue to getting past this issue. When you post back with the info I will also get a ticket opened for you so that we can examine things and exchange some details in private.
Thanks to both of you for being so thorough with your testing and getting the results posted here, hopefully we can get these issues resolved quickly if it turns out to be an error in the code somewhere.