Even on a real PC, any number of things can cause keycodes to get eaten. Skype, for example often gets blamed for this. But if I saw this behavior, the very first thing I'd check for is keylogging malware. Yes, I know, Macs aren't often infected, but I'll bet their hosted Windows is.
You have the further complication of running Windows itself as an emulation. Does Parallels provide keyboard shortcuts for switching/managing environments? If so, gobbled keycode opportunitues right there.
Thanks very much for these suggestions. I doubt either malware or Parallels are to blame, though, because....
a. It's an institutional computer, with daily updated virus files, and I don't download anything EVER through Windows (except software updates). No guarantee, of course, but I doubt that this would be the cause.
b. When the problem surfaces (which is some time after entering FM), it is *local* to FM. I've never had the problem in MS Access, the only other product I use frequently on Windows, and when it happens, I've loaded Word and other things, and the problem is not duplicated there.
c. The problem is discussed on Parallels forums (for an older version, however), but in those cases, it is global to all apps....