Thanks for posting. Apologies that your system is not working as expected.
Please contact Dell Tech Support for assistance with this BIOS issue. You can contact Tech Support at 1-800-624-9896 or 1-800-288-4410, or you can initiate a chat session http://dell.to/2v4snVm
If you did the bios update addressing the Spectre threat, you cannot downgrade that bios. I contacted support and this bios will block any downgrade. Unfortunately your stuck with what you got until Dell releases improved bios updates that address problems. If you look around Microsoft has released a patch that disabled some updates causing some of the problems. It was released through the Windows catalog download site and not through Windows update. This is because not everyone is having issues and you should not defeat the security patch because it will leave your system vulnerable to Spectre. Obviously their is no simple solution here, so be patient or try to defeat those earlier Windows updates to see if you system becomes stable. I imagine soon enough we should see fixes come out that address the Windows and bios issues. I pretty sure Dell does not want a repeat of what has already occurred so its doing better testing before releasing new bios updates.
The Microsoft patch can be found here: