That's very weird, but possible. I've heard of cases where the orientation of the drive when the drive was formatted affected whether or not it worked properly in one orientation or not. If you are able to successfully boot it up, backup the all the data to an external hard drive, and reformat it in the orientation that is best for you, and then copy back over the data. Dantz Retrospect Express is the best Mac OS 9 and earlier native backup program and Mac OS X native. If you are just running Mac OS X, Bombich.com's Carbon Copy Cloner is also good.