I've read a few posts from others who seem to indicate that TASCAM doesn't respond to email.
I've just reinstalled my windows XP operating system ... complete with reformatting the drive and reinstalled Gigastudio as well. The registration process has not resulted in any response from TASCAM.
Of course, I'll call the phone number, but I was wondering if the lack of email response was typical from TASCAM. If I recall, Nemesystech always responded when I needed to new key after reinstalling. I'll have to call TASCAM from work, but that's fine ... as long as they answer the phone.