So, Apple pushed iTunes 9.1 which is safe for overall jailbreak, but it kills blackra1n for Windows users, in particular for tethered jailbreakers. As promised, iH8sn0w released a fix for this bug called: BlackBreeze.
All you have to do is download BlackBreeze, and click on “Fix my ra1n!”. In case the tool won’t find the blackra1n.exe file, you will need to browse for it manually. That is it. Enjoy.