I've been fighting for several months now with my 17" LCD Studio Display. It came with my first G5, and I was never able to get the USB ports to work with that computer(stock Geforce 5200). I gave up trying as I ended up using a 1080p LED monitor and upgrading the card to something without ADC(6800 Ultra). I've cycled it through a couple of different G4s and graphics cards, and generally have had no luck with getting the USB ports to work. It's currently connected to my Quicksilver through a GeForce 4MX. A few months back, I bought a 20" Cinema Display. The USB ports worked on it, but I ended up returning it due to pressure marks on the screen. Much to my surprise, when I reconnected the Studio Display, the USB ports then worked on it. Somewhere along the way, I had to unplug the Studio Display and when I plugged it back in, the USB ports were again dead. Just on the off chance that it would work(but not really expecting anything) I downloaded the drivers for the 23" HD Cinema display off Apple's website, and all of a sudden the USB ports were alive again. I've left the display undisturbed since then out of fear of once again losing the ports. I disconnected it yesterday to install the Geforce 4 Ti that I bought. Unfortunately, that card was dead, so I ended up replacing the GeForce 4MX. I've now, once again, found myself without USB ports on the monitor. I'll also add that when I lose the USB ports, the hub does not show up in System Profiler. As I'm sure you all know, this a little more than just a simple annoyance as it is impossible to control the display brightness. For some strange reason, I've also not been able to successfully boot into OS 9 when an ADC display with dead USB ports was connected. Does anyone have any thoughts on what could be wrong given the symptoms I've described, or at least for things to check or try?