I had this and found the solution within the forum of the T-Mobile UK web site. Flash your G2/Hero from the latest version for T-Mobile from the HTC UK support web site. Do this even if you are on that version already. After flashing and the phone is booting up it will grab the update and install just fine. When it's worked your build number will be 184.108.40.206 Make sure you have the latest version of HTC Sync too.