Much like my color picker issue, this just started happening. I had used substance fine when I got it on Saturday. No issues. But over night, and today when I run substance, it runs like butter. However, if I go to do anything else, like click on my start menu, my system locks up. Substance, again, still running smoothly (this can happen with an empty scene as well). After a while, either I'll get a "microsoft windows has stopped working" dialogue, or I'll just give up and reboot. If I "close" microsoft windows, my desktop disappears, but substance continues to run like butter.
This only happens with substance. I've reinstalled multiple time, to multiple hard drives, rebooted dozens of times, but with no luck.
