Update on my previous post:
It does seem to be specifically an Excel problem -- inactive windows will scroll, except when either:
- Excel is the active window, in which case no other windows will scroll; or
- any other window is active, in which case all windows except for Excel will scroll.
This includes MS Access, the only other Office application I regularly use. Access gets along fine with other apps; only Excel has the problem. I think I'll pass on the uninstall/reinstall "fix" until there's word that this actually fixes the problem that
has by now obviously been shown to be a side-effect of the recent Windows Update.