delphi unblock downloaded file

when users in windows xp and above download file to ntfs driver, the exe is blocked and claimed "this file is come from other computer" etc. i want you to code me an exe , when it is downloaded and excuted , it will unblock itself . after i excuted it for one time , the property of this file should be unblocked and the warning message removed. you should realize this in delphi source code, there's some tools on internet can unblock files, like [login to view URL] etc. so i think it should be realized in delphi too. if you can finish the application , please upload the bin to freelancer, once i take your bid. please don't use modify registry to realise this , i need code to unblock the limitation. thx