I was playing a game with a friend in the PBE to test out the new champion. Three bots, myself, and the friend against five custom bots. I was playing Pool Party Ziggs (because I couldn't select Snow Day), and the friend was playing Vi.
Upon getting in, the screen froze for five seconds, blacked out for five seconds, returned to a frozen screen for five seconds. Rinse repeat for another thirty seconds or so. Then the screen just froze. All game sounds gave way to a drone that damn near deafened me. Waiting didn't fix it, and I was forced to hard reset, being unable to CTRL-ALT-DLT or alt tab. Trying to get in twice more after that yielded the same result.
Can I ask y'all to go ahead and try updating your video drivers, and then test to see if the issue is still occurring after doing so? If you're unsure of how to properly update your drivers, we've got an excellent knowledge base article here that can help you out with that.
If you're still having problems after doing so, can I ask for your updated Dxdiag information? Thanks!
Edit: In addition to your dxdiag, I'd also like to ask for your most recent r3d log from when you last encountered this problem.