[CRASH]

Over the past 2-3 days I've been experiencing sporadic drops of FPS in my games, across various champions and situations. The FPS counter says that it's stable at 55-60 FPS, and while it usually only ever flickers between 59 and 61, the drops are clearly much more noticeable than what is being reflected. The only commonalities between them appear to be:

1. tabbing out and back in temporarily fixes the lag, although it doesn't last long.
2. It only appears to occur mid-late game.
3. When the game ends, as the Nexus is exploding the screen freezes, my computer plays an error noise, and if I tab out I find a popup that says "Failed to create dump file : " (error 183)". If I close this, another popup appears with the text "The instruction at 0x01586220 referenced memory at 0x00000000. The memory could not be written. Click on OK to terminate the program". Any help on solving this would be greatly appreciated. Regards, Wazikamawata