Has anyone else run into this? I just acquired an MOTU MIDI Express XT USB (replacing an older unit that used a serial port). I'm running 10.2.4 on a DP G4. I have configured my USB with the XT plugged direct into one of the two ports on the G4, and an Epson C80 direct into the other. My keyboard, mouse, and floppy drive go into a Belkin self-powered hub which in turn is plugged into one of the ports on the back of my Studio Display.

What I find is that with the XT switched off, the Mac can't shut down! If I tell it to, it goes through the shutdown cycle, there is a momentary change in fan speed, and then it comes right back up. Worse, if everything is shut down, and there is a power failure, when the power is restored the Mac will start up by itself. (In the past week we've had thunderstorms, and I've had to get out of bed in the middle of the night twice to shut it down.) The only way I can make it shut down, short of yanking the power cord, is to either (1) hold down the power button as it's trying to start back up, or (2) switch the XT on. If the XT is on, the shutdown works normally.

But I don't want to have to leave the XT on all the time. Some Usenet posts I've seen suggest that it might be a problem with the amount of current being drawn off the USB bus, but why would the XT -- a self-powered device -- be drawing current from the USB when it's switched off? I'm thinking about buying another hub and running the XT through that to see if it makes any difference. Ideas?

I have the same problem with a Pismo powerbook and the MOTU micro express USB. If the MOTO is not powered up, the piz can't shut down. I'm not using a hub, just connecting directly into the computer's USB ports.

I have found that unplugging the USB cable from the back of the powerbook (at any time, even just before shutdown) will allow the computer to shut down properly when the MOTU has not been turned on.

I suspect that it is a driver problem although you may be right about a hardware issue with the USB power. I've tried MOTU support and get the usual no reply. They haven't updated their driver for about a year...

BTW I also have a USB fastlane and this interface doesn't have this problem.

I found the same thing. After doing a little experimenting, I determined that if I run the MOTU through a Belkin 4-port hub (the square one with the clear plastic top) the problem goes away. I bought a second hub so that the keyboard etc. can have a separate hub and the MOTU has a hub all to itself. This seems to work and it hasn't caused me any USB performance problems.

I, like you, wrote to MOTU tech support and got no response. I also noticed that they haven't put any new articles in their online tech database in some time.

Thanks for the tip about the hub, I'll check it out.