Hi Bob,

I'm having this same issue and I think it has to do with dithering. I use AO on SBIG STT-8300 and I get error similar to this:

(taking 600 sec. exposure, Clear filter, binning = 1)
(using Normal readout mode)
(dithering 1.0 pixels std-dev on guider)
(guided dither - moving guide star dx=0.2 dy=-0.6 guider pixels
(AO - waiting 20 sec for new dark frames...)
**Guider waited for 10 sec and never got a measurement
**Guider stopped or lost star just before image acquisition

I want to explore whether the dithering is causing the problem. I'm using ACPS. Should I just disable dithering in the scheduler plan or is it somewhere else as well?

Wes