[moved] HFSS 2014 (v. 15) issues with Windows 10

I got a new PC with Windows 10 .... everything is good with this Windows EXCEPT I cannot run Ansys HFSS 2014 (v. 15) which is the main software I use for my research ...

I installed it but it always crashes once starting the software (HFSS) .... I cannot open any file ...

I tried the new ANSYS EM Suite 16.1 (Ansys Electronics Desktop) on same Windows 10 but it gave same issue (cannot open)

I appreciate any advice ...

Should I remove Win 10 and install Win 7 or 8?