Computer won't see ipod

Ok, I'm really fustrated. My Third generation ipod seemed not to be working right. It would stop right in the middle of songs and stuff. Have a service plan. (Thru Best Buy) I bring it in. It's gone for 2 weeks. Get it back and they say there is nothing wrong. They did every kind of test they could and couldn't find anything wrong. But now the Hard Drive has been wiped clean.

Now I go home, Hook it up to my G4 powerbook. I've got a couple of gigs worth of music. After an hour or so, everything stops. I worry about disconnecting the ipod because of the big red flashing warning on the screen. But after a full day I've got no choice.

My ipod is sill empty but now the computer won't see it. In fact, now any computer won't see it. If I hook a computer up to it, the flashing red warning sign appears but it doesn't show up in itunes of on the computer. If I go into itunes preferences, it says "no ipod connected"

Now I know I should bring it back since a have the service contract but I really miss my pod and don't want to wait another 2 weeks to be told it's fine. Plus I'd like to try download music one more time.

Anyone have any idea's?

Thanks

Jeff