Possible bug - received a call on Viber Desktop during game, became unplayable - [CRASH]

Windows 10 OS - only had this once, but posting as a particular event happened that caused the game to go haywire.

Got a call on the desktop version of Viber during a game. I declined it but the volume on the game went. I continued on playing for a while, but from there on the game got much slower. Eventually all I could only see frames every 1 second or more. When I checked task manager, I had a lot more instances of LeagueOfLegends running. Memory was at 53% (16gb ram), processor looked fine. It kept getting slower and I then lost the use of Windows Explorer too.

(other programs I had open - Microsoft Edge, Google Chrome, Spyder, Notepad++. In the tray I had AVG, iCloud, & OneDrive - neither signed in, Dell Smart Settings, Cisco AnyConnect - unconnected, and other usual stuff like sound, batter etc.)

No idea if this is reproducible or not, here's how it happened to me - start a normal co-op vs. AI game. Receive a Viber call during it and Decline it.

Cheers.

BBR