If you have recently installed/upgraded to firefox version 3.5.5, you may have faced the right click problem on pages. I experienced the same and found a solution. Now right button click works well for me.
This is a very simple fix but you have to know the secret..lol. If you are facing the same problem, you may try uninstalling “Yahoo Toolbar” from firefox addons list (Tools > Add-ons > Yahoo Toolbar > Uninstall).
Just wanted to share this simple but important fix.