Like you, I also have experienced issues with 5G 60GB and 30GB iPods and compounding the issue by trying to use iTunes to fix it is just as bad as asking a hooker where the nearest church is.
Apple used to make and update but still publishes something called "iPod Updater" and it can be used to reload it w/o using iTunes.
http://www.apple.com/support/downloads/ipodupdater20051117.html
The iPod Wizard site also has the entire history of these iPod Updaters at:
http://www.ipodwizard.net/showthread.php?t=7369
And the latest version which I recall is going to be more recent then the one I listed from apple is at:
http://www.ipodwizard.net/updaters/windows/iPodSetup%202006-06-28.zip
I once had a 30GB 5G so bunged up, I had to find the first version of the OS with all the bugs just to make it responsive again, then had to update the software and hold my breath.
then I sold it as used on Amazon and found a buyer in less than an hour and for market price.
then just bought a cheap HP/Compaq iPaq and loaded the songs onto the SD card, you can get 16GB SD cards for lower cost and just copy your songs onto those and spread them out on multiple cards if you have too, iPaq's have headphone jacks and also tingeee little speakers and they don't freeze up as often and are easier to fix and find answers to issues than trying to figure out how to move a clickwheel and press an arrow button just to access hidden menus that never fix the problem.
Best of luck.