Like many others, I too have had problems with my beautiful RGB fans (6 LL120s) flashing and blinking for no apparent reason. I immediately realized it couldn't be a hardware issue (6 fans suddenly flashing at the same time? I don't think so), so I started looking at the software chain.
If you look at the Device Manager under Universal Serial Bus controllers, you will see an item called 'Corsair USBXp Driver' (see attached image). Highlight it and select 'Uninstall Driver' either from the toolbar, or right-click (context) menu. Your lights should go out at this point.
Right-click on the USB Controllers item (actually any item will work) and select 'Scan for hardware changes'. This will re-install the driver, and you will notice your fan lighting is now working again!
Hope this helps folks who have been frustrated with this problem. I rather suspect a number of problems with RGB products are related to this driver. Now let's see it Corsair can figure out how to fix it!
Terry