Okay, so this is a strange one. I was playing World of Warships last and in the middle of a match the sound went out. The indicator light on my speaker was still on, so I knew the speakers had power. I alt-tabbed out of the game, intending to flash up my browser to play a Youtube video to see if I had sound there. I clicked on the Chrome icon, but nothing happened. After clicking the icon a few times, I tried to open Firefox instead. Still nothing. Then I clicked on the Start button and the menu opened as usual (running Windows 7). However, I couldn't click on anything. The side bar was frozen to the screen even when moving the cursor or clicking away. I then tried to bring the game back up but that didn't do anything either. I tried to alt-tab back into the game, but all that did was cause the little screen that pops up to become frozen in the middle of the screen.
At this point, I attempted Ctrl/Alt/Del. This, perhaps unsurprisingly, did nothing. The computer was well and truly locked up except I could still move the mouse around. So I hard rebooted the computer and once I reached the desktop I almost immediately had the same problem. Chrome started to open but froze on a white screen. I tried to launch Steam and it verified its installation, but proceeded no further. After that, it was a repeat of the former. This time, I rebooted into safe mode and was able to get the computer to function normally. I then attempted a system restore to a few days earlier. Once the restore was completed, everything seemed to be working normally. I had sound, the internet and other programs would load, and I played a quick match of Cold Waters which ran normally. Then I got on this forum to compose most of the above with the intention to ask what could have been causing the problem. I kept checking as I was typing to make sure everything was still working and it was. When I clicked submit after not quite ten minutes, the same issue occurred. Chrome seemed to be trying to submit my post as the little circle next to the tab was spinning, but it wouldn't post. I tried to open a new tab but it wouldn't and so on and so on, see above. For about 30 minutes I sat in safe mode with networking and everything seems fine. I can access the internet and Steam even works fine.
I've run sfc /scannow and malwarebytes. No issues found. So, does anyone have any ideas about what this could be? Software? Hardware? I don't even know where to start. I've never seen something like this before and don't have a clue what it could be.
Processor: Intel i7 4770k 3.50 ghz
Motherboard: Asus Sabertooth z87
RAM: 8gb DDR3 1600mhz Corsair Vengeance
Power Supply: Corsair RM 850mw
Graphics Card: Gigabyte Geforce GTX 1080 G1 Gaming
OS: Windows 7 Home Premium
CPU Cooler: Digital Storm Vortex 240mm Radiator Liquid CPU cooler
Storage: 120gb Samsung 840 EVO (OS)
Storage: 1tb Seagate Hard Drive