you said "my PC" as in single pc, so that threw my theory out the window. my router sometimes causes this issue with my 2 or 3 pc setup. 1 pc will lag to all get out (5000-8000 ping) while others are 150 ping or lower. restarting my cable modem & router fixes it every single time. but with just 1 pc i'm not really sure if that would be the same issue, but its worth a try.