I've accidently upgrade to iTunes 7.6 - I'm on Mac, btw. - and now it won't install the iPhone firmware 1.1.2 anymore.

I restore to 1.1.1 and jailbreak and OktoPrep, but iTunes just quits with "Error 5" when I try to do the update to 1.1.2.

And when I delete iTunes 7.6 and install 7.5 it won't recognize my iPhone anymore.

What do I have to do to get back to 7.5?

I hope this hasn't been answered yet, because it didn't find any answer through the search.