I attempted to download the latest version of Adobe Flash Player (v. 11.7.700.169) from the Adobe site (http://get.adobe.com/flashplayer/). After the file downloaded, I double clicked on the file and the file disappeared. I downloaded the file again and when I tried to run the file, I received the message, "Only a single instance of this application can run." I rebooted the PC and removed the prior version of Flash Player and then I attempted to download the latest version again. At this point, the same results occurred.
During the adobe download process, I always unchecked the box for the McAfee security plan offer in the initial download screen.
My version of Windows is XP Home Edition version 5.1 with Service Pack 3. Browser is Firefox 20.0.1.
I would appreciate any help you can provide.