I DID IT!!!! After looking all over the web and trying everything,... This method on this thread works. This is how I did it,...
Do everything again but don't use the 4.2.8 ipsw! I found out that apple does not sign it no more. Instead I used 4.2.6. That was the last major update. Follow the procedures but DON'T use the Redsnow to jailbreak it at the same time. Just downgrade to the stock 4.2.6 ipsw then upgrade to the 4.2.8! from there I used snowbreeze 2.7 to jailbreak and PRESTO!!! It worked!!! make sure you still use Tiny Umbrella and start the TSS Server before you begin the downgrade then when your done...hit the Exit Recovery. You should then be on 4.2.6! Download 4.2.8 stock and upgrade with that. Then jailbreak it with snowbreeze 2.7. I'm a happy camper now and you'll be too!!! Enjoy!!!