Buffalo External HD not recognized on MBP

[jd87]

I have a 250 GB Buffalo external HD that has been working fine with Mac OS X 10.4. For the past three months, I was using the drive on a separate Windows computer. Now, when I hook it back up to the Macbook Pro, it's not even showing up.

I tested it on another Mac, and it seems to have the same problem. When plugged into a different Windows box, it worked. The external HD has a switch to automatically turn on when it is plugged into a USB port. Only one of the ports will work to automatically turn the drive on. Both USB ports are working for other things (iPod, mouse, etc.)