When trying to launch L4D2, a window opens, saying Completing Installation. After rising from o to 1 percent, it says Steam service component must be installed to run steam properly. I have the component installed, and it refuses to install again if I try. I have tried deleting the component and redownloading it, but nothing works. I have been able to play on the same machine before, in windows 8. I am now using 8.1. Please help.