Hi, I have problem with my brand new Apple LED 24: In order to manage brightness (by keyboard or in the preferences pane), I must have the USB-cable plugged into the computer. Now, it seems as if the only USB-port my 24 likes is the top front one! (Mac Pro) If I try the lower one, or any one of the three in the back, nothing happens. And as if that wasn't enough: after a while, it looses the connection, and I have to re-plug it. My first thought: could this be due to the fact that I'm using an USB-extender (5 metres)? Is there a signal loss or something?... Thanks.