Some time ago my (fully patched) XP desktop contracted the dreaded Random Calculator Popup, although in my case the calculator only pops up a few times a day, usually when I'm typing furiously.
I've scanned for viruses with Symantic Endpoint Protection, run Spybot, and they didn't find anything. There is no shortcut assigned for the program in the Start Menu under accessories. (I searched the hard drive and there is one other copy of the calc.exe program in the i386 directory. It doesn't seem to have a shortcut that I could see.)
This post suggests it could be a keyboard hardware issue, but I find that a little hard to believe.
Maybe Ed Bott will ride to the rescue again.
Or maybe I really need to find a machine on which to test Wordperfect X14 in an xVM virtual box under Ubuntu or SUSE ….