Downloading ipsw never moves

I did a jailbreak on an AT2 at our vacation cabin and all worked fine.  Now I get home and trying to do another one for home but when when I click the Create IPSW it goes to the downloading screen but just stays there forever with absolutely no progress.  I have left it there for over 30 mins with zero progress.  The internet works fine as I am doing this from the same computer as I wait for some progress.  Any suggestions

I stopped and restarted it several times and finally it started working.  Got all the way through to asking for iTunes to do and told it yes.  iTunes gets started then after a while gives me a error 21.  Have done this twice now.  This is where I was at several months ago which is why I did one at the vacation cabin and it worked fine.  Must be something in the router security settings or something.  Any advice would be very helpful.

Do you have the power cord plugged in when you get error 21? I found I had to make sure it was removed while restoring the software or I got this error.

No not plugged in power just the USB.  As I understand the instructions, it said NOT to plug in the power cord.

Fair enough - thought I would check.

A number of people have found that they seem to need the Power cable plugged in to initially get into DFU mode.    However if you do that, once DFU mode has been achieved it seems to be important to remove the power cable before attempting to restore the jailbroken firmware.

Doing this from Win XP.  Just for heck of it, I did it from my daughter Mac NetBook and it worked.  Same DLS, router, etc.  Yet I used my same computer when it worked at our cabin.  Different router, but exact same computer as I carted mine up there.  This would seem to eliminate it being any anti-virus, etc on my box and using her mac seems to eliminate any DSL/Router issues, ports, security, etc.  Got it done, but I need to resolve since I know it’ll come up again.