I think this has been discussed here before and I know that my county neighbor and imaging mentor, Steve Reilly has rarely had this problem as well without a clear-cut cause or resolution. It may well be a Maxim-DL issue, in fact I bet that it is, but I thought I'd post here first. Last night I got up at 3:45 and checked on the status of things. ACP had been frozen for 3 hours, apparently waiting for a Maxim-DL image download. Maxim-DL appeared to be frozen as well, and reported that it was "downloading" and the cooler was "off." This is the first time that I have experienced this in over a year of imaging. Ultimately, I had to shut everything down and restart, and then Scheduler/ACP/Maxim-DL worked fine for the rest of the night. I do not believe this is a USB cabling issue or a power issue. A few months ago I updated the power supply when I was having sporadic issues with cooler shutdown at 100% power, so there's plenty of power now. The USB cable run is short with solid connections. I'd appreciate any thoughts or updates and I'll post this on the Diffraction website as well. Thanks!