Few days back, Gears of War on PC stopped working, courtesy of an expired Windows digital certificate. Meant people owning the game couldn't play it. Few days later, it's OK! Everything's fixed.
Epic have since released a patch for the game, which will turn up as a mandatory update. If by some chance you were genuinely affected by this news, and were actually playing Gears of War on PC instead of simply stroking your chin and chuckling at the ineptitude of the whole thing, you can download the patch below.
Gears of War [Microsoft]