I'm having a few issues with downgrading. I want my iPod Touch 4th gen from ios 6.0.1 back down to 5.1.1, but it's not going so well.
First I tried redsn0w. Logged on to the administrator account in windows xp, launched redsn0w, went to the restore option, selected the 5.1.1 ipsw, fetch blobs "remote" (I seemed to have accidentally deleted my local blobs), let redsn0w do it's stuff, and then this happens: Redsn0w hangs for a couple of seconds when "Uploading IBSS" and then crashes! Windows gives the error report, as usual.

So that's a no go. Next option, downgrade via iTunes 11.

Still under administrator account, launched redsn0w, went to the blobs section, stitch, ios 5.1.1 ipsw, remote, let it do its thing for a while, and enter pwned dfu mode. Next I browse to C:\windows\system32\drivers\etc, open hosts with notepad, and add "74.208.10.249 gs.apple.com" to the bottom of it, then I save the new hosts file as hosts, like it was. Finally, I open itunes, it pops up with the itunes has detected an ipod in recovery mode, blah blah blah. Shift + restore to the newly stiched ipsw, and itunes attempts to restore it. Unfortunately, itunes gets stuck at "verifying ipod restore with apple" for a few minutes, then throws me error 1601 or 1602.

Cannot fix it no matter what. I even used tiny umbrella to download the shsh for my device on firmware 5.1.1 and stitched it. still nothing.