I wonder if it would be possible to fix this issue, couldn't find it in the keyboard shortcuts so wonder if it is a bug. 
In any case it is very annoying that when you hold down spacebar too long or double click it, then you jump to the start of the song. We got w as a shortcut for that, don't really need another one... 

Hi. I get this on my laptop as well. I can not remember that it has happened before, but i might be wrong.

Happens for me too, feels glitchy.

I don't get the double click thing, but holding spacebar does jump to the beginning. Never noticed it before. I wonder how long that has been in Sonar? Bug? Undocumented feature?

I see this as to be expected if you have return to zero checked in the Preferences. Pressing the space bar plays Sonar pressing it again will stop it and RTZ. Holding is similar to that though I can't see where one would want to do that. Sonar is not a word processor. You will not be adding space to the time line by holding the space bar.

CRTL W will toggle space bar behavior from stopping where you are, to return to last mark. 

Right. Crtl + space will pause.

Holding the space bar will send Sonar multiple space bar clicks. How long you have to hold it for this to happen will be controlled by the Windows setting for character repeats when a (PC) key is held pressed.

I use the space bar when auditioning clips and sometimes instead of one tap for stop then another to start again I'll hit them too quickly and rtz.

This happens to me and it's annoying. I have to make sure I don't hit the spacebar too quickly after stopping playback. Usually, it's not a problem unless I have a large project that acts a little sluggish. This is when it gets frustrating.