I know exactly what error code he's talking about.

To combat gold spammers, blizz blocks your IP from being able to create more than X number of trial accounts.

I know this because my bf opened 2 trial accounts for his 3-box mages, and I opened 4 for my 5-box setup. I got an error code activating my last two "recruit a friend" trial accounts (all same name, info, e-mail).

Then I logged onto account admin from work, tried the EXACT same trial keys and exact same contact info and was able to activate it fine.

My suggestion? Go to a library/friend's house/work and try to activate the rest of the trial accounts. I'll bet you they activate just fine.