Recently I've been having problems with my 4th Generation (ClickWheel) ipod turning on. It would just stop playing suddenly and then only display an apple support URL. My ipod wouldn't turn on (well only display the url). After a bit of googling, I found an answer!
I should first mention that everytime I would get the support url instead of the full ipod menu, I would be able to hear the ipod's harddisk whir. The noise was barely audible albeit unusually loud. Thus I figured that the problem was mechanical -- I've had the ipod for almost 3 years now.
To quote the solution I found in an online forum, "its fixed now - but I didnt use the updater. In sheer anger at it, and a hatred of ipods that developed because of this, I smacked it against the wooden desk I was at... then it made a funny whirring noise - hard disk? When I turned it on, it worked again. Who said violence isn;t the answer?"
I actually tapped the ipod against my palm and magic! The ipod worked. I didn't even have to perform surgery on my ipod like this guy.