Really check all the auto timings are correct for EACH channel, and that they are the SAME on ech channel.
My gigabyte board (with crucial ram) has been known to set each channel to slightly different settings, like one channel at T1 and one at T2.
It would then get stuck on the second pass if IBT (and crash arma too), with lock ups when browsing.
As soon as both were manually set to T2, sorted (a couple of other things were different but cannot remember them now),