Obviously, you updated to 3.61... and the only way to do that without internet is by updating to 3.61 via a new PS3 game with the update on it. Don't know how you could have done this without knowing... unless a roommate messed you up. Good luck
I agree with both, but that depends if Sony a playing by the book. and not disregarding the rules because there dealing with hacked units.
You didn't say what firmware you was on, and what homebrew you was using, was MultiMan ftp on? was it set to check for game updates?
Can you say that all the homebrew you installed is what it says it is? has Sony swapped messed or modified it, or a Sony sympathiser ? Theres at least a handful of ways this could happen that I can think off. Sony said them selfs they can control the ps3 regardless, and one of the ways is though the xmb startup when it visits all 14 odd sites before you know it.
But this one is the rootkit that's in the 3.55 ofw rushed update, they didn't just remove downgrading they added remote control. just a thought.
Also if you plug your media into a ps3 thats on 3.61 and then plug it into your computer or worse a ps3 on cfw don't be to surprised if funny things start happening.
There is no possible way a PS3 with CFW running multiman backing up a game closed multiman, connected to the internet, downloaded a firmware update, installed it and rebooted without someone pressing a button.
Stop the conspiracy rubbish, one of the roommates obviously did it and wont fess up.. just lock the thread.