When in Boot Camp (also, for me, VMWare seeing the Boot Camp Partition) the Exposé buttons, (the buttons to either side of the Mighty Mouse) function by default as a browser back button. Since I have a habit of squeezing these, it is really rather annoying when your browser keeps jumping backwards on you. However, I did find this little programme called X-Mouse Button Control that allows you to disable that (and really customise your mouse to no end). Just another little Freeware programme that everyone should know about.
X-Mouse Button Control