Exact same thing happened to me, 3 times First time I lost everything, I had ALOT was just about to get the last 2 armors I needed for achievement (spooky and 1 more piece of spectre.) when it happened the first time, I uninstalled and reinstalled then started again around 24 hours later it happened again this time I uninstalled and went thru everything on my 360 and erased everything I wasn't using then cleared system cache and turned it off for an hour just to be sure I tried everything I could, then I reinstalled and tried one last time. It just happened again...also around 24 hour after I reinstalled, oddly enough.
I have never used glitches or cheats, I just think it ruins the fun, even now I look forward to restarting, after this problem has been fixed.
One thing I have noticed is that since the last update your avatar has a tendency to phase partway or fully thru walls.
I have only one profile on my xbox so I do not know why it keeps saying the file came from another profile there isn't one and never has been one.
If you guys manage to fix this before Halloween can you please send me an e-mail? I would like to collect the Halloween outfits before it is too late and I have to wait another year (I know you can change date of xbox, but I never do that too risky).
Thank You for your time
Best Regards: A Rabid Terraria Fan