Dell Precision 5530 "Unsupported GPU Processing Mode"

Has anyone else had problems with a Dell Precision 5530 developing a GPU error problem and refusing to work with any Resolve 17x versions, when it was working fine before...?!?
A few days ago, following upgrade to 17.4.3, Resolve refused to load, with the following message:
"Unsupported GPU Processing Mode
Please review the GPU drivers and GPU configuraton under preferences."
When I click ‘Update Configuration’, there is no way to alter the GPU configuration as both
Intel HD Graphics 630 and AMD Radeon Pro WX Vega M GL Graphics are greyed out and labelled
‘Unknown, not supported’ (...?! ...SEE ATTACHMENT... ...and please note...deselecting 'Auto' produces NO options for manual selection of CUDA!)
Blackmagic Design said that the way the GPU is reported suggests a system problem, not a Resolve problem, so they cannot assist further. The Dell 5530 is fully updated with all drivers etc... and nothing related to any function or other software is reporting any issues.
I confess I am totally confused and mystified by this...
Is anyone out there still using a Dell 5530 successfully with Resolve 17?
Had any problems with GPU? Solved any?
Any advice most welcome... THANKS!