Windows 7 + CableCARD? Do not install KB3004394!
Details are a bit sparse, but it appears that the recent KB3004394 patch breaks content protection on Windows Media Center for all CableCARD / Digital Cable Tuners (DCT). Early word was that it affected all platforms, but Silicondust says it’s safe for Windows 8+. So if you’re running Windows 7 probably best to skip that one for a while.