Intel recently admitted that its latest patch for "Spectre" was essentially worse than the bug it was supposed to fix, as it was causing computers to spontaneously reboot. Now, Microsoft has taken action by issuing an out-of-band patch for Windows 7, 8.1 and 10 that disables that fix for Spectre variant 2. If you're experiencing the problem you'll need to download the update, as it won't yet install automatically.