client crash - won't load past 100%

hey all so over the past 3 or 4 weeks now about 1 out of 15 games will hit 100% while loading in and then randomly leave me in the load-in screen while everyone else loads in and starts the game. It effectively locks my computer down and prevents me from alt-tabbing and won't load into game no matter how long I wait. the only way I can rescue my computer from this nasty bug prison is to restart and relog. it mostly happened while playing normals so friends could yell at me and I could force the restart, making me not think much of it. on sunday however I hit 0 lp, had the bug, and then got demoted from a "leaver" game I couldn't control on my first game after I hit 0 lp. on a happy note yes i did win the next games to repromote but thats about 75lp that I could have put towards my climb which makes me sad. I have tried completely reinstalling league and was wondering if anyone else had this happen and found out how to fix it?