Weird problem, if my PS4 Controller is plugged in (via USB), Steam will not launch/login/do anything. If I unplug it, Steam works perfectly. Using default/built in drivers on Windows 10, no 3rd party stuff like the DS4 software.
If I plug it in while it's working perfectly, things just freeze up again, until I unplug it.
XBox360 USB controller unaffected. Any ideas?
edit: to clarify, if i play a none steam game, it's also not really a problem. only if i need to do anything via steam then i have to unplug the controller