I just had to replace my system drive (re-installed same system software - 98se) and now when re-installed, GS 96 (v 2.0) won't recognize my piano disk --an essential step to be able to enter my registration code. The CD drive seems fine--it's installed and run lots of other stuff.
Open the Registry. Go to HKEY_CURRENT_USER, Software, Nemesys, Gigastudio,User. There should be a key that says UserKey and it's blank. You should enter your registration here (create the key if it doesn't exist) and then it won't ask you for your piano disk anymore.
Just wanted to follow up with what I found out at Tascam support in case it's helpful to someone else in the future.
For some reason, after reinstalling 98se (with all current updates) GS 2.0 would not read my piano disk to complete the install/registration. Once I updated to 2.5 it the piano disk was recognized and the problem was solved. I had to contact Tascam support to get my download code since I couldn't enter my registration number until I upgraded.