Okayy,
so as a lot of windows users are expiriencing, it's hard to get back to the 1.1.1 firmware from 1.1.2. But you don't even NEED to be on 1.1.1 to jailbreak the 1.1.2 firmware; just use iBrickr to downgrade to 1.0.2. Then, once done jailbreaking the 1.0.2 firmware, go to Browse applications>Greg's Installer 2.63(im not sure if that's the exact number version)The click it and it will upload to your phone. From there, install the following items off of installer on your phone: BSD subsystem, SSH client, MobileFinder, and most importantly OktoPrep.after those things are installed, upgrade your iphone. once your iphone is running on firmware 1.1.2, on your computer, head over to: http://conceitedsoftware.com/iphone/site/112jb.html

download the file provided by the link once you arrive at that page. Once you unzip the file, click on the executable file named jailbreak.jar
Once you click on it a box should pop up with a password box containg the word alpine. Change this ONLY if you have changed your SSH client password. next to the password box is a checkbox, check it if you want, which is what i did. FINALLY, press the "jailbreak" buttton and let it be for how ever long it takes.
there shouldd be some instructions at the end telling you to re-boot your phone. After you re-boot your phone, unlock it and your phone should automattically reboot itself. then youre done!
i hope this works as well for you as it did for me