Projector/PC over DVI to HDMI Cable

Looking for assistance with my setup which I thought I did my homework on.

I have two Dell 5100MP Projectors connecting to a Dell Precision 3500 Desktop with ATI FirePro V3750 GPU. For cabling I have 35' hdmi's to a wallplate and then a monster dvi - hdmi cable (MONSTER CABLE - V600 THX Ultra HDMI to DVI 4FT).

During post of the PC Everything looks fine (obvious a low resolution), but when the OS boots in to 1024x768 the screen becomes very distorted and the projector flickers on and off clicking. My first guess was the signal loss from the distance of the cables. As a test I hooked up the PC to the projector directly with short monster cables and the picture was perfect.

So back to the long cables, I hooked my Tivo Series 3 with HDMI over the long 35' cables thru the wall plate and ran a 1080i video and the picture looked perfect.

I hooked the PC back up and the projector will only display at correctly at 800x600 anything higher and it is distorted.

Where is the breakdown? If my Tivo plays over the long cables at 1080i why wouldn't 1024x768 work?