popup when using trackpad on mbp

[bt22]

I have a 13" MBP running Mac OS X 10.6.7. I have noticed lately that when using the trackpad I will get an annoying popup box giving me the options of... back, reload page, open in dashboard, view source or save page as. I am not sure what I am doing differently to cause this popup, but it is very annoying. I have to single tap the trackpad to get the popup to disappear and then I can continue scrolling. I checked in system preferences to see if I could see an option that might be causing this, but nothing stands out. Any help would be greatly appreciated.