I just bought a first-generation 5GB iPod on eBay, and it's working great so far, except for one big problem: it won't wake from sleep about 90% of the time. If it goes to sleep through being paused for more than whatever the cutoff is, or if I put it to sleep by holding down "Play", it won't wake up again, and I have to reboot it with by holding "Play" and "Menu". It seems to be worse if I put it in "hold" mode by using the switch on top; if I don't put in hold, it will sometimes wake, but be "stuck"--i.e., non-responsive, and I'll have to reboot it. Once, it actually hung right in the middle of playing a song, but that hasn't happened again.
It's running iPodOS v3.1, and the first thing I did after I got it was run the "Restore" option in iPod Updater to completely wipe it clean and reset it. If anyone has any idea why it's misbehaving or what to do to fix it, I'd really appreciate the help.