Something very strange occurred last night: While running an ACP plan, MaxIm displayed "Reading CCD Camera" in the guider area, and nothing more happened -- it was hung, and I had to abort the plan. But immediately after, I clicked the Track button in MaxIm, and it guided fine, with no "reading...." hangup.

This occurred multiple times. ACP started the plan, plate-solved the target, and started guiding. But after four (four, every time) successful guide exposures, MaxIm hung up after displaying "Reading...." And every time, after I aborted the plan, MaxIm guided successfully when I clicked the Track button.

All the aCP logs indicate guiding is working.

This is the exact same plan I ran just three nights earlier to get M5: http://astronomy.mdodd.com/stars-04.html Nothing changed.

The only thing I did in MaxIm was to increase the "Delay after sending correction" from 0.1 to 10 seconds, trying to test "bump guiding" suggested by A-P's Roland, with a long delay between uide corrections. But after a couple of hangups, I set that back to 0.1 second. It made no difference -- MaxIm still hung after four guider cycles while the ACP plan was running.

The only other change was two "critical updates" to the Windows OS (Win 7 Pro). I don't know how this might have affected ACP's interface to MaxIm, but it seems significant that the hand-up problem occurred after the Windows updates.

I have just rolled-back those updates using the two restore points they made, and will test again tonight if the sky clears. Fortunately, I also created a manual restore point before installing the updates, so I ought to be able to go back there if necessary.

Any ideas what might have cause the guide camera hangup?

--- Mike