RESOLVED!
did you try to update your kernel or do a general update?
dnf update kernel
or dnf update
or a downgrade of kernel-devel?
dnf downgrade kernel-devel
The system was fully updated at the time (6 hours ago).
Now the rest of the kernel*4.10.14* rpms are available and I just
updated wih no problems. Virtualbox now works.
All's well that ends well. I guess.