Microsoft Autorun v2.1 improves safety
In recent years, malware has sometimes found it's way to USB based devices (e.g., Flash Drives, MP3 players, etc). On infected PCs, many malware agents will search for these devices to add a copy there as well. Microsoft's latest changes to Autorun helps prevent these devices from starting automatically and is available by Windows Update now. The Auto run process is a key technique used to infect other systems. However, users can always start these devices manually. It's a best practice to always scan your portable media devices periodically for malware and always do this when the source might be untrusted
Microsoft’s Autorun update v2.1 now automatically deployed from Windows Update
QUOTE: Microsoft have moved their Windows Autorun V2.1 (967940) update patch from optional updates to automatic updates. This is the same patch that was released in last month’s patch Tuesday. When Windows update is next run, this patch will automatically be selected to apply to your machine. This is more likely to affect home users, as companies should be using group policies to control how USB autorun settings operate. Expect one or two calls from confused family members on why their favourite autorun USB stick application has stopped working.