Is there having any mechanism to check for our ip address before registering? This may be a reason that they detected multiple account creation attempts for the same ip, thats why you couldn't creat a new account there. You should check with them with your old accont deactivation problems.
I too thought it was due to multiple accounts, but I'm getting the same error and same message "this account cannot be used, please sign up again" when I tried to sign up in other hosting sites like 00fees.net. I'm really frustrated now.