Hi !
Just so you are aware: we do not support I-deas 6.5 on Windows 10.
The first certification on Win 10 was I-deas 6.6. We just released I-deas 6.7 last week, which also supports Win 10.
If you are doing a fresh install at this point, to be the most "future proof", I suggest downloading and using 6.7.
One of the biggest issues we found when we were first testing I-deas on Win 10 is that most operations require Run as Admin, because of the way I-deas is structured (it calls other scripts and executable that access files on the OS - Win 10 has locked many such operations for better security).
So be sure the CMD window you run with is Run as Admin and also set any short-cuts you execute the same.
I added some notes on this point to the README for Win 10 when we released 6.6.
I don't think you have an issue with the DOMAIN name. It has not changed from NX_IDEAS_6 since I-deas 6.0 (we probably will never change it).
I also suggest looking the previous thread where and I discussed this. While none of the tips helped in his case (he posted here the final solution he found), some of those other tips might be your situation.