You should ask the people having the issue to switch graphics cards, PSU and RAM since this >90% smells like a memory/power issue. I think you've just gotten unlucky and collected a few similar reports of people having memory corruptions. I am guessing you cache renderings and that is why the issue sticks around until you re-render.

If you want to reproduce it yourselves then perhaps try pointing a hairdryer from a distance at the various components until they start to create trouble, or alternatively just overclock them towards the breaking points.