When I start up my MB Pro with my iPod attached, comp hangs at grey screen. Will not start in single user mode, or target mode either until iPod is physically disconnected.
Try using "Disk Utility" to check both your hard drive and your ipod drive for errors (to fix any errors on your hard drive you'll have to boot off the Leopard DVD and use the disk utility there).
The presence of an iPod at startup may cause the computer to start up improperly. Disconnect the iPod prior to turning on or restarting the machine, or try placing a hub between the computer and the iPod.
I have this some problem between my Macbook and my 5G iPod. A hub does not change the problem. The problem existed (for me) on Tiger as well as now on Leopard. Is this a problem everyone has? I have owned other iPods and never had this problem before.