Camera works fine at ground level, powers up then shuts down at installation site.

We have a Sony network camera we're trying to install. It works fine at ground level, but when I try to install it at our mounting location- appx 75 feet from the router and power source- it powers up, does its pan/tilt start up routine, and then appears to just power down and I can't see it on the network anymore. I've tested the power line and I'm getting power (obviously, since it's powering up to start). I've also tested the network cable- If I bring a laptop up to the mounting location I can get internet access through the cable just fine.

Other than a defective camera any other suggestions what the problem could be?