My SSD is only 120GB's, and so space can be precious.
Do you have framerate un-throttled when you attempt this? Do you fat-finger it or accidentally hold it down longer? I don't have 1.6 on this machine so I can't test it out myself right now, but this sounds pretty serious. This is exactly the kind of bug we need to hammer out before declaring 1.6 gold.
I could have a look. I know that it would be incredibly easy to just disable screenshots. But I don't like how I've been making new builds of Sphere with more and more stuff disabled. On the other hand, it would be pretty easy to write a screenshot bit in script.What if you try running it in compatibility mode? That may block events that have a attrib value higher than 255 (big 'may' there).