I see 2 likely issues:
1: Projector does not like 1600x1200. The projector is simply not capable
of this. The manual will state the projectors capabilities.
2: Marginal wire. You have a wire that is barely good enough to pass
1080p, but not good enough to pass 1600x1200. Believe it or not, 1600x1200
requires much more bandwidth than 1080p and therefore is much more
sensitive to cable quality.
