I have been using Zorin 17 for a couple of months and I am very happy with my switch from Windows.
I have a lot to learn but the people on the forum are very helpful
I decided to upgrade to Zorin 18 and I keep getting the system simply freezing and the only way to escape is to switch off the PC.
It appears my hardware may be too old to support Zorin 18 - I am using a Dell Optiplex 790 with a i5 2400 CPU and 16GB memory.
So I have decided to ditch 18 and re-install 17.
Did You tried to switch to Xorg? What Graphics Card You have? Are Secure Boot and Fast Boot in BIOS disabled?
I did switch to Xorg - I use a standard Intel HD 2000 graphics card.
I was not aware that Secure Boot and Fast Boot could present with issues.
Yes, unfortunately they can cause Issues. So, it would be good at least to try it with disabling both. But okay, when Zorin 17 works for You, that is fine. It is still supported. So, You can use it.