If you use AVG FREE AntiVirus, be sure to update with the 2014 Version.  Be careful when installing – you need to change the selector button to Free Version during the installation – if you don’t you will get the Free Trial, and it will expire if you don’t pay.  We have been using the FREE version for years without any issues.

http://download.cnet.com/AVG-AntiVirus-Free-2014/3000-2239_4-10320142.html?part=dl-10044820&subj=dl&tag=button&cdlPid=11014801