We just have different understandings of the definition of random, yours wouldn't hold up where I work, where I work what I have is considered a consistent non random bug.
Completely random is relative to your perspective of random.
Who knows, maybe it's perhaps a problem with your system, an inherent flaw in DirectX, or something else entirely different.
On a more productive note:
Is it just Alt-Tab that causes the problem? Have you tried the Windows key and then re-selecting the game? Have you tried to interrupt it by bringing up the task manager (via Ctrl-Alt-Del)?
Does doing any of the above cause the same issues revealing that it's in-fact the minimizing of the game that causes the issue?
Oh and Ascii, this is computers we're talking about. Nothing is random :wink: