Why do I have to change antivirus software every six months?

May be...

I have had my laptop for a year and I'm on my third anti virus software. Why is my anti virus software malfunctioning after every six months? I started with Norton then went to BitDefender, and now I'm using McAfee.Thanks in advance.

try Avira or AVG

I had problems with all those 'mainstream' ones but these, avira specifically, are dope. no problems

They should be good for 12 months, (then need updating) I've always used McAfee, which in 5 years, has never failed me.
There are free and online internet security systems, that apparently can protect your computer for up to 3 years, I don't believe these to be as good but I know people who use them and swear by them, NOD 32 being a good example.borg collective quotes