With Maxim 6.12 and the SBIG latest driver doing 'traditional' guiding (No AO-X) I've started to get a lot of occurrences of the guider stopping unexpectedly, particularly between subs. It doesn't do it every time but I'll guess that its over 75% of the time.
I realize this is probably not an ACP problem but though I'd mention it here for tracking. I've also sent a PM to Adam at Diffraction about this.