Hi Bob,
After searching the forum...looks like we are having this similar guider problem in Jim's observatory in Texas. I have attached a Log file so you can review.
Guider is Starlight Lodestar used in 2x2 bin mode. I had first updated the driver in hopes of resolve the issue; however the issue persisted. Last week Jim installed a new USB guider cable in hopes to resolve the issue, again no luck. So we are are a loss, whether it is either a hardware or software related issue. We are using latest versions of ACP/Scheduler/Maxim, also the issue occurs on say 1/2 of the block plans that are run. Below is the setting within ACP Guider Tab