Thanks for reply.
Unfortunately I had to totally reinstall Windows from a USB using the windows creation tool. It now works but it's two days out of my life speaking with Dell out of warranty repair group.
I'd suggest people do not try this fix at home - although I've no evidence to say that it wasn't just a "regular" update corruption issue.
What device on your system is using the iastora.sys driver? If you don't know how to find out, ask.
@BrickeddIf the driver is being used on your SATA controller, perhaps updating your Intel SATA driver will help and move it to the iastorac.sys driver. If not, it may have to go to the storahci.sys driver which is a Windows basic SATA driver.
I have one system which will not use the newer drivers and it is in that situation now. If you need to change the driver, set msconfig.exe to boot your system into safe mode and make changes there. When you are finished, reset msconfig.exe to boot back to normal mode. You may have to work on when you rename the iastora.sys to .old but if you are in and will reboot into SAFE MODE, you should be OK.