if you are using a disk, did you follow this advice?:viewtopic.php?f=5&t=4771
if you can see the boot menu when starting from the disk; you can try the following, as soon as you see the Zorin menu, press the "Tab
" key and type "nomodeset
" (you can also try "acpi=off
" if nomodeset doesn't work for you) then press enter and see if it boots, there is also and option to boot in safe mode
, you should try that also.
Have you tried Unetbootin on a USB stick?:http://unetbootin.sourceforge.net/
Let us know if this helps.