I think I may have found the problem. I had downloaded a new MeLabs programmer beta program and hadn't really used it until this week (and found this target device problem). Reading the enclosed notes, for once, I came across a statement indicating that not all devices would work after the upgrade and I should re-register the OCX for the USB programmer. I did this and now everything is okay. Here is the relevant info, for future reference, for others:
USB OCX Installation:

"The melabs U2 / USB Programmer requires registration of an OCX file for
support of the USB functions. This file is normally registered when the
melabs Programmer software is first installed. To register the OCX with
Windows:"

regsvr32 HIDagentXControl1.ocx

Thanks to those who responded.