former This is a total _guess_, but... I've recently been working with some 11/23's I just bought, and I too had similar flakies appear mysteriously with one of them. I'm not sure exactly which of the below finally cured them, but you can try the following things (one of which finally did it for me - after sitting for a long time, the connections can possibly be slightly flaky): - re-seat all the cards in the backplane - re-seat the chips on the CPU card (take them out _very_ carefully, slowly levering from all 4 corners - they are brittle, and you can fracture the carrier if you get too aggressive) - re-seat all the jumpers on the CPU card I also discovered and repaired at least two cold-solder joints (one was one of the pins for W1, the master clock control - the pin was actually loose when I wiggled it). Cold solder joints are pretty insidious - they can work fine for a while, and then start to give problems. Do you have more than one memory card that you can swap in/around? That might be it, too. Noel