I had the same problem -- freezing at Zorin logo on boot for 18 Lite using older hardware (but not all that old) but not 18 core. I was baffled as well, and tried all the troubleshooting that has been advised, including booting through the boot menu. But no joy.
Then I saw this post, and thought, mouse dongle, which was the only thing remotely related to bluetooth on the machine. So I took the dongle out, turned the machine on, and 18 Lite booted without any problem.
As noted, this does not happen with 18 Core using even older hardware, and I've never had this happen on any other Xfce distro, and I have tried most of them that aren't Arch. Hopefully, this is a bug that will get worked out.