You might consider installing a decoupled panel. 4 resilient clips, two sections of metal furring channel and a piece of ply.
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Posted via Mobile Device
Just decouple the projector, like above, instead of the entire ceiling.They make vibration isolation kits for projectors. i.e: http://www.htmarket.com/vibab.html
I don't have that problem with my projector, but my pot lights flicker when my kids jump on the floor above. The joists in my house are only 2x8's wherein something thicker might be better.