Mouse & keyboard unresponsive + grey striped screen

My system has been working fine for half a year now (a while back my mobo failed and I got a new one along with a cpu due to sockets), but strange errors have begun occurring.

Specs: (mobo and cpu are fairly new, rest are ~4 y/old.)
Motherboard: Asus z97-a
CPU: i7 4690k
GPU: Radeon HD 7950
PSU: Silver Power SP-SS750M 750w
RAM: Corsair 8GB (2x4GB) DDR3 CL9 1600Mhz VENGEANCE
Probably irrelevant:
Mouse: steelseries rival 300 (engine 3 installed)
Keyboard: Logitech G11
Monitor: BenQ XL2411Z (plugged into gpu with dvi)

First issue: While playing CS:GO, every 2-3 minutes my mouse goes unresponsive, and about 5 seconds later so does my keyboard. 10 seconds after that I hear the usb disconnection sound, then my mouse and keyboard start responding again.
I tried CS:Source too, same thing happens.
This hasn't happened while not playing a game. Instead...

Second issue: I haven't been able to reliably reproduce this error, but the first time it happened I clicked on an embedded youtube video.
The moment i clicked, the screen went grey with lines all over the place, some flickering, some not.
I didn't wait to see if it would fix itself with time, since I was scared it would screw up my computer even more.
I forced shut down.
Happened once more later, not sure what I was doing when it happened.

Where do I begin to troubleshoot? Both of these issues began occuring at roughly the same time (1 day apart).
Thank you so much for any help you can give me!

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The first issue is the mice's fault (in the process of RMA), the second issue remains a mystery.

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Since it was Youtube try one thing.

Google "Disable Flash Hardware Acceleration."

It's an old issue you see on old cards.

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