Are you able to get the system to boot without the SoundBlaster card? Not many people use sound cards anymore because most mother boards have decent audio already built in... Anyway, I am guessing there is a conflict with one of your installed components and when you mentioned the sound card and having to blacklist intel audio, the lightbulb came on for me....
It's an honour to get a reply from the main man! Yes the onboard sound was fine for earlier versions of Zorin, the latest however, built on Ubuntu 18.04.2 doesn't like the onboard sound and a user of Ubuntu found the same issue with same chipset on a different motherboard. I followed CwF advice and swapped the battery - I only purchased the mobo last October, but noticed on boot the date went back to 2016 so probably good that I did that. However, I made the fatal mistake of updating the BIOS from 4024 to something like 4207 which added PXE boot items for network boot which I have disabled and now it comes up with GRUB rescue and won't play nice with any installed GNU/Linux - I'm posting this on a live edition of Makulu Lindoz 15 March 2019 release. I can see Feren OS drive and Zorin drive but can't boot into same. I think I will try and reinstal Zorin as I hadn't got anything saved there. Will keep you posted. Thanks to both you and CwF for input.
Post Merge: May 03, 2019, 06:10:34 PM
Well I got it sorted in the end - for a full explanation as I can make it, please head over to here where you will see the images and save me reinventing the wheel again here.
You are not allowed to view links.
Thanks guys for all your guidance.
[Footnote: the reason I couldn't boot into any of my GNU/Linux drives was down to the fact I had managed to disconnect SATA cable from Makulu Drive where after a recent update it took control of GRUB!]