Dumb comments below aside, I’d like to point out this exact same thing is happening to me.
I moved a lot of files to the side (backed up, removed from system), then reinstalled WC3 and downgraded NVIDIA graphics drivers; problem is “lessened” (less occurrences), but the game still crashes from time to time (Blizz gives me a code to send to them, I’m about to, next time this happens, like it surely will).
Something to note here is that right now my GPU does not overheat anymore (stays in a safe range), but when this started happening around a month ago, it would go to 80-85°C, which is the failsafe by default, so screen would be “software unplugged” but then it would come back fine, and even allow me to keep playing; right now though the game crashes without remedy.