I arrived to work around 9:20 this morning. Around 9:30, Workrave requested me to take a rest break. I was surprised since I never observed a bogus rest break request, and suspected someone else might have used my PC just before I arrived. That would have been unlikely, since I have a strong password and only one colleague knows it, but thankfully, the statistics allowed me to check for sure. And sure enough, my daily usage was under 15 minutes when I checked.

This is the first time I notice such a problem in more than 2 months of usage. I use Windows 8.1. Sometimes, I notice that the rest break timer freezes, as it the mouse was moving. Perhaps this is due to micro-vibrations. But I suppose that can't explain this bug, since this would be considered activity time.

(In reply to Filipus Klutiero from comment #0)

Was this restbreak, by any chance, labeled a "natural restbreak" (this should be visible on the break window).

Workrave might ask you to take this "natural restbreak" when the screensaver activates and/or when the screen is locked. This way, it is possible to trigger a break prematurely.

I don't remember seeing a natural restbreak, and I didn't pay attention to that, but I doubt it. I am 90% sure I was working when this happened. The screen was not locked and there is no screensaver.