you might have 2 probs goin on.
If you are using firewire: i bought a firewire card AT THE APPLE STORE. 3 months later the belkin card stopped mounting my ipod. no errors, it would charge but not mount. I go back to complain and the apple genius actually told me that card only works 30% of the time. WTF! Try connecting via USB borrow a friends. worked for me.
I've also had the problem with the song skipping. Resynching fixed it for me. Make sure the songs are ok in itunes.
if all else fails, reformat the ipod and just resynch it to your library. It's a pain in the ***, but usually works (like rebooting your computer!)
ps im assuming ur ipod isnt physically damaged, dented, or making weird noises or displaying cryptic characters...
The iPod randomly stopped mounting on my desktop or iTunes, also won't mount in disk mode, when I try to play a song on the iPod itself it just starts skipping through songs, displaying the title and then switching to the next song in the playlist, displaying that title, and so on.
Fixable? FUBAR? Help? Please?