Trouble Hacktivating iPhone 3G 4.2 for T-Mobile

[sephrothm2]

I have been trying to activate my iPhone 3G for T-Mobile for 2 days now.
info:
iPhone 3G
ios: 4.2.1
baseband: 06.15

Jailbreak: redsn0w 0.9.6b5 to 4.1 with tiny umbrella (for the 10xx error)
sn0wbreeze 2.1 to ios 4.2.1 creating custom firmware and restoring with that.

downloaded ultrasn0w 1.2(for unlock for other carriers) from cydia
but it does not work. I have tried searching for other methods but this one is the only one I can find. It seems to work with most people.

Another method I tried that worked before with this iPhone:
SAM module to unlock the phone
This method needs me to deactivate the iPhone through redsn0w. But the problem with this is that redsn0w gives me the ramdisk error while uploading everytime I try to deactivate the iPhone with redsn0w_win_0.9.6b6.
To try fixing this I tried the set run to administrator, run as xp service pack 2, set affinity to run on all cpus, and it still gives me the same error.

[Stray]

Have you tried a different computer

[sephrothm2]

Yes, I have tried it on my brother's laptop running Windows 7. Mine is running Windows Vista.

[Stray]

Have you disabled 3g?

[sephrothm2]

Just tried it a couple of times... not working neither.

[Stray]

What about downgrading to 3.1.3 also since it is a 3g do yoh know if your bootloader is the old or new one. You may be able to downgrade your baseband to 05.13.04

[sephrothm2]

How can I check what bootloader I have?

I just realized I kind of posted in the wrong forum. I will try downgrading if I still can't find a fix for my problem. Thanks for your help!!

[Stray]

Ummm no problem