Upgrade help needed, with Windows

I was trying to go ahead and upgrade to 2.7.1, using the Automatic upgrade plug-in. It worked great last time. This time though, for some reason Windows won’t let me unzip the backup file. It tells me that “Windows has blocked access to this file to protect your computer”. I went into the properties and clicked the button to “unblock” the folder, but it still won’t let me unzip it. I just want to make to make sure I have all my files before I go ahead with the upgrade. Any thoughts????