I know this isn’t the horizon part of the site but I was hoping any of you might have an answer…I just bought horizon last night and popped it in today to see how it works and so as soon as it loads it goes to do a title update and after that it asks me what storage device I want to use and I select the 360s HDD and right away I get the box that says it appears your profile has been tampered with. you can not proceed…what gives? I have looked into the storage area under horizon and all the files that are there look fine no (!) or anything and ive even deleted my gamertag and redownloaded it and that didn’t fix it and no one but me has access to my profile…please guys help
I have the same issue, been working fine the past few months but today I get the message “Your profile has been tampered with” even though I haven’t changed anything and haven’t transferred any content.
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Contact the developers with all the details, including gamertags on the console, at forzafb@microsoft.com.
I just got this message. 
I cant proceed past the start screen.