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I've always assumed it comes up when all switchable (alt+tabbable) applications are busy, and can't re-render their interfaces for some reason. So Windows can't finish switching to them. But that's a wild guess.
I've only ever run into it when I have three or fewer applications open, which is so very rare that I haven't encountered it enough to bother me.
But I'm pretty sure I have encountered it from time to time in Windows 10 of various releases. (I never had Win 7)