Problem solved -it isn't the 942.
The remote freeze problem started when I moved my 942 to the lower portion of my AV cabinet. In that part of the cabinet it is behind closed doors so I connected it to my HK HE1000A IR repeater. The HE1000A has a red light that goes on when it receives an IR signal, but the light stays on for about 60 seconds after my MX-500 sends the macro to turn everything on. The other day I opened the cabinet door and disconnected the 942 from the IR repeater and ran the macro again. The 942 worked perfectly. I then hooked the 942 to the repeater again AND kept the door open - 942 didn't work while the HE1000A light was on. I then decided that the HE1000A was sending a signal during the time the light was on that was confusing the 942.
Wanting to figure out why the light stays on for 60 seconds I turned everything on one-by-one. In doing that I found out that the light only goes on after the TV (32" Samsung LCD) turns on AND the picture comes on. The HE1000A sits right under the TV so I moved it outside the cabinet and behind the TV and everything works perfectly. I then moved it back into the cabinet and when the TV comes on, if I hold my finger over the HE1000A IR sensor, the light goes out. Remove my finger - light comes back on, stays on for 60 seconds, and the 942 doesn't work during that time.
It seems as if the Samsung puts out an IR signal that the HE1000A picks up, but somehow filters out after 60 seconds. I have moved the HE1000A to the shelf below the TV and it works better, but it stills picks up a reflected signal for about 10 seconds.
Anyone seen/heard of this before?