Sounds like a JAVA issue.
Uninstall JAVA and then reinstall with the version on the 12 installation disc.
Once you have Archicad installed hen you can update JAVA if you need to.
Barry.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10