[diddly]

Recently Steam VR kept opening randomly on my laptop.  It's not actually random, I was using Firefox at the time.  If this happens to you, turn off the openvr setting in Firefox.

I started running into the issue after an update. To resolve, I went to about:config, and disabled the key dom.vr.openvr.enabled

Source: https://www.reddit.com/r/SteamVR/comments/6ixwvi/steamvr_starts_when_i_open_firefox/