If I die my mouse stops working properly. I can still click on the screen, but I can't change the view by moving the mouse to the edge of the screen or click on the map.
Thsi happened twice already and the solution was restarting the game.
1. I was playing Zilean
2. I got killed by Lee Sin and after respawn the mouse didn't work properly
3. I tried different USB ports, but that didn't help
4. I used alt+f4 and restarted game, this fixed the problem
I had spellthief's edge, rod of ages, and boots of speed at the time of death (maybe void staff not sure)
1. I was playing Karma
2. I got killed my Nocturne after Respawn again the mouse stopped working properly
3. I repeated step 4. of previous game.
At time of death I had Frostfang, Morellonomicon, Zhonya's Hourglass, Amplifying Tome, Blasting Wand and Sorcerer's Shoes.
I'm not 100% sure, but both times I died in Drake pit.