I've been running into this problem lately - I installed gMax fine, no problems, and everything runs under the administrator account (with which I installed the software).
However, when I log in under another account, Tempest won't load. gMax loads correctly, but Tempest does not - and it complains that "mtlgen.dlt is missing". Keep in mind, the program runs correctly under the admin account, just not under any other account.
Anybody run into this?
Also I have copied Makemdl and FSModelExp.dle into the main plugins folder in GMAX