Something else to take a look at in the meantime; A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums
This lists all of the currently known software conflicts w/ the engine. While none of them list symptoms that match your issue, there is always the possibility.
Also, although it’s probably not going to help as you mentioned that the issue isn’t project related, could you send a project (even if it is a blank one) where the issue occurs for you? It’s best if we be as thorough as possible and exhaust all possibilities.