I have very strange problem.

When I start mining with all 4 cards PC just hangs and I have to power it off. (tried with drivers 14.4 WHQL, 14.6beta, 13.12 all hangs)

When Mined with 3 cards : 1) 0,1,2 and
                                     2) 1,2,3 it works ok.

Even When I try with BAMT by following guide
http://www.reddit.com/r/BAMT/comments/28xu3i/add_amd_146_drivers_and_djm34s_optimized_sgminer/
It hangs with mining with all 4 cards.

Any one please help me out?

PC:
AMD 145 sempron 32 bit
windows 7
4x 280x powercolor OC