If we're talking tech tips, can anyone explain why I occasionally get a grey screen while I play?

Its something that only really happens to me (theres someone else who uses the headset thats a half foot shorter than me)
We're using a vive with 2 sensors that are placed maybe 2 meters apart, about 6 feet in the air.
On occasion I get a 5-10 second drop of greyness, the game doesnt pause or anything, and as I'm sure you can imagine its pretty annoying when it happens.
Not moving outside the designated play area or anything.
Known issue, bad hardware, something else?