Won't compile any scenes

“UnrealLightMass-Project.dll and embree.dll are either corrupted or not able to run in Windows.” Something to that effect. I am using Windows 10 64-bit with 32GB of ram and an NVIDIA NVS300. The games run fine in the editor but simply won’t compile. Also, the Editor menu can be selected but when it drops down, it is not visible (moving a mouse beneath the menu will display the tooltips).
YouTube suggested using GPU version of LightMass, but I don’t see a Plugins tab on my Editor. Very new to Unreal
but love it so far.