Exact same problem with latest version - 5.1.889. As soon as I installed it and it searched for an update, CPU usage jumped to 50% and stayed there. Tried everything and finally restored previous version - 864. Problem gone. As a double check, reinstalled 889 again - problem returned. Back to 864 for second time - problem gone again. You have a bug here, folks. Something ain't right. Running Win7 on a Dell Vostro 1500. Very experienced user.