Spacebar keystroke won't stop.
My iMac recently started having a problem where the system is receiving a spacebar keystroke that won't stop. I think this is what's happening based on spaces added to onscreen text in different apps, and from the KeyBoard Viewer that shows the space bar constantly depressed.
This is NOT a keyboard peripheral issue. I've tried multiple keyboards. I've also tried disconnecting everything connected to the mac and rebooting. The issue persists. I've had it stop after many reboots (which seems coincidental). I also reset the PRAM and that seemed to have fixed it, but now it's returned (after about 24hrs).
I don't know what else to try. I haven't installed any new hardware in the computer since I bought it (upgraded ram). It's worked fine for 1.5yrs.
iMac (27-inch, Late 2013), OS X El Capitan (10.11.5)