The really big 'however' and the part that leaves me scratching my head - once I level during play, that all goes away. FPS is a solid 60 and both the keyboard and mouse respond without issue. If I quit or just reload, it goes back to ignoring me again.
I know it didn't do that before, but there have been quite a few computer changes since I last played so I can't figure out what is causing this, or how to make it stop. :( Very frustrating.