Utility to reset attribute on files in Windows

When an executable file is downloaded from a web site to a windows PC, a 'blocked' attribute is set on that file. While this attribute remains set, windows will display an "Open File - Security Warning" window each time that file is run (see attached screen grab: [login to view URL]). This is annoying, and is the problem to be solved. The attribute can be reset by clearing the check box on that message window and clicking the 'Run' button. It can also be reset by opening the properties of the executable file (see attached screen grab: [login to view URL]), and clicking on the 'Unblock' button. I require a utility program which will clear this 'blocked' attribute without human interaction. It will run as a console mode windows application. It will possibly receive one command line parameter, which is a path name to the target folder. If that parameter is not supplied, then default to the current directory as the target folder. Your program must recursively scan all executable files in the target folder and its sub-folders, and reset the 'blocked' attribute if it was set. Language to be used is open to your choice. You may rely on a minimum environment of Windows XP SP2 upwards, and .NET framework v2.0 or later. No operator interaction is required. Console mode output should at least include program version number, and a list of files processed. Program name is to be '[login to view URL]'. Delivery required is source code and compiled ready-to-run program. No DLL's - any library routines should be linked at compile time, apart from those in .NET framework. I own the copyright. Unlimited right to reuse any and all of the code is granted to you.