display driver crashes after Sleep Mode?

So I wake the computer out of sleep mode and use it for a few minutes but get this message soon afterwards (along with the computer freezing).

1. The computer "slows down," music/video lags, mouse response also lags
2. Screen goes black for a few seconds
3. Screen returns to normal, but mouse and keyboard not functional aka "frozen"
4. Message pops up: "Display driver NVIDIA Windows Kernel Mode Driver, Version 196.21 stopped responding and has successfully recovered."
5. Since I still cannot do anything, I must do a hard reboot.

Apparently, despite this message, the driver has NOT successfully recovered, or at the very least, hasn't fully recovered.

What could be causing this problem? I am using S3 Sleep Mode.

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