I have been playing minecraft on my 360 offline for quite some while now (my adapter broke), but the other day i went to a friends house with my harddrive so we can play on his xbox, i downloaded the recent title update thru his ethernet cable, after that the game was on the trial version when we tried to play. I assumed it was because it was a different xbox. So today, I came back home, put my harddrive in my xbox and tried to launch the game but an error came up saying, "The game couldn't start. Try downloading the game again." I have never had this problem before, so I am wondering if I should delete the recent title update, since I can't re-download unless I buy a new adapter or ethernet cable. Please help. I dont want to lose all my progress.
You are going to need to either fix your network adapter issues or you are going to port your XBox License. You are right in why you only got tutorial mode on your friend's XBox, this is because your profile wasn't native to that particular Xbox when you purchased Minecraft, and you will have to do a License transfer before it will unlock fully. (I ran into this problem myself about a year ago).
Your saved files should be fine, but if you are worried about them, you can back them up on a USB stick (there are instructions on how to do that online). You will likely meed top uninstall your Minecraft Application and re-install it. Just don't load any of your previous saved games until you are fully upgraded to the current TU... there have been major file corruption issues reported when trying to open a save game file that was created under a later TU as the current running version of MC that is trying to open that file.
Your saved files should be fine, but if you are worried about them, you can back them up on a USB stick (there are instructions on how to do that online). You will likely meed top uninstall your Minecraft Application and re-install it. Just don't load any of your previous saved games until you are fully upgraded to the current TU... there have been major file corruption issues reported when trying to open a save game file that was created under a later TU as the current running version of MC that is trying to open that file.