Hi. I've successfully installed Lion on both my mid-2010 MacBook Pro 13" and my 2007 iMac. However, on the iMac I'm able to navigate (back/forward) in Firefox by sliding four fingers from left to right on the trackpad. However, I'm unable to do that on the MacBook Pro. I'm pretty sure that I didn't change any settings in System Preferences that would change the gesture. Can anyone help me? I'd really love to be able to navigate Firefox on my MacBook Pro with the gestures... Thank you!