first do this tutorial
http://www.iclarified.com/entry/index.php?enid=367
download your os, this has download links to all the os versions for all devices: http://www.felixbruns.de/iPod/firmware/
then in itunes hold control and shift(or control and alt or something correct me if im wrong) while pressing the restore button, you should have saved your os so go to the file and double click it
Here's my problem My Ipod touch 3gen that stops playing music for 2seconds when connected to my pioneer avh p4100 deck. It does this about 3times a song, i didnt have this problem 2hours before i upgraded to the new firmware(4.1). I have been reading the forums on how to downgrade but if i didnt save the shsh blobs or whatever then im screwed. I have called Apple and they told me they dont downgrade, once the ipod has upgraded. The problem is this update is bad and now im stuck with it. I hope somebody has a fix cause Apple isnt helping.
http://www.gadgetsdna.com/how-to-downgrade-ios-4-1-to-ios-4-0-iphone-firmware/4689/

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