I think I have finally found the problem, and will know for sure Monday.
The USB cable where it enters the electronics on the back of the board has a bad connection. This was tricky to find because there were several times when I was told to uncable/recable/restart after we reloaded drivers and so on. It always looked like what we had done via the computer that solved the problem.
The same problem kept returning and finally it made sense to me that the problem was the connection between the cable and the board. Yesterday the problem returned twice and both times we reconnected the USB and the problem went away, and eventually returned. It only makes sense that this is the problem.
Monday prior to the start of school I'm going to recable the USB connection. Being a rather large man (6'1", 250 Lbs) this is easier said than done. The board is only 3 inches from the wall, and the cabling runs behind the board. I'll let you all know if this works as a permanent fix.
Thanks to you all for your suggestions. It was the step by step process that allowed me to eventually find what seems to be a rather simple problem.