I dont thnk there is not any restriction for number of GPUs in CGminer, i am using Ubuntu system with Cgminer 3.2.7 where number of GPUs didnt made my program crash,

By far i am sure you have already solved this issue of yours.  I have similar issue regarding cgminer for altcoin(fork of ltc ) which i created for learning purpose. When the block is formed it gets rejected giving the reason of Diffculty, but why the senario is weird is because i have set the difficulty to be as low as possible i.e 0.002 approx, normal cpu minning is working properly and generating blocks with some lag in conformation time but CGminer is not even meeting the difficulty. I would appericate any help or advice