When some antivirus suites expire they may block the internet "for your protection." I've written this many times and disagree on that action.
As to moving files, some USB drive should be fine but for now use another PC to run the McAfee uninstaller ( it's at http://www.bleepingcomputer.com/download/mcafee-consumer-products-removal-tool/ ) and then try to backup your stuff again.
For a free antivirus I use one over at Ninite.com Here's why I use Ninite:
About 3 months ago, around the same time my MacAfee anti-virus expired, my browser(IE, since Google Chrome wouldn't work on it), and other programs I have been using on the desktop all but disappeared. I can't browse on the computer, and the only program I can successfully use is Second Life. I would love to be able to move files off this desktop so I can restore and purchased an external drive for this purpose, but with the computer not working well I am unable to do even this simple task. I noticed that there was a file listed under favorites(hqghvmeaylnf.exe)and I googled it, seems it's a virus.I'm not sure what to do at this point, I just want my old computer back. It's a 2009 Dell, sorry I can't find the information about specifics because that information doesn't pull up when I try...Please help