I'm on Win10 at work, purged everything Blender related from my PC, all files, cache, settings, registry, everything. Updated Nvidia drivers. Still getting this weird issue on a fresh 2.8 (official) install that 90% of my UI is not there and I cannot interact with the program at all. Any ideas what could possibly cause this? A few days ago this was still working fine :\
This is caused by the PYTHONPATH environment variable being set to something outside the scope of blender it seems. If you make a bat file with:
set PYTHONPATH= blender
Place this in the same place as the blender.exe and then run it.
This will bypass the system environment variable and should load as intended.