I'm not throwing the idea out that it is on Blizzard's end, however we all need to remember there are zero day attacks out there so not all "harmful software" is in every antivirus/antimalware database. We are all connected to the internet and connect to websites and download files from outside sources which means right there we are all at risk. This is very real and is not meant to be paranoid. All you can do is surf safely by visiting legit sites manually instead of using links in emails, etc. So many fake emails are sent out regarding players accounts just to have you log into a website made to look like the official and now that you've entered your information, you've just given the thief your information. This information applies to everyone regardless of your expertise in computers or computer security.
Some simple tips to keeping your computer safe:
1. Keep your software up to date.
-This includes your operating system, virus definitions, java, flash player, browser and any other software you use like Adobe Reader. All of these items listed have in one way shape or form been under attack and have been used to exploit whatever the attacker is after.
2. Browse safely!
-Do not visit websites you don't know such as clicking on a picture on google that takes you to the website hosting this photo. Once you visit that site you're now connected to it and can be compromised.
-If you use Firefox you can use addons like noscript which blocks java and flash on websites but this does take some understanding on how to use this addon to allow you to see the stuff you only need to see. Another addon for Firefox is addblock plus which is pretty self explanatory by the name of the addon.
3. Email... yeah 
-Email has been used to scare players into clicking on a link that is provided in that email body and logging into their accounts to verify them or save their account from being punished for some random negative deal. 99% of these are fake and is actually how your account is compromised. If you get one of these emails, it is best to log into your account by manually typing in the website information in the URL bar at the top of your browser and logging in the way the gaming company intended you to. You can go as far as submitting a ticket to customer service or call the customer service number provided for that gaming company if they offer it so you can be sure.
-Please be careful with links in your email guys!! Just because a friend sent you an email doesn't mean they actually sent it. Email accounts are compromised daily and are used to spam people on their contact lists with the information the attacker wants you to click on. If a friend legitimately sends you a link, it doesn't mean you can still trust it as they may not even know it is malicious. Same goes for file attachments. You as a user need to be responsible and take action to learn what is safe and what is not. When we drive our cars we don't just run into trees on the side of the road because we didn't know we were supposed to stay on the road. Be responsible.
I hope this information can save some of you from trouble at some point while being online. Another valid point you want to think about is you are not, generally speaking, safer by running more than one antivirus program at a time. You should choose one antivirus program and keep it up to date. You can still use an antimalware program to do scans and what not because those are not actively scanning your computer and won't conflict with your live scanning antivirus program. For example my choice of antivirus software if Microsoft Security Essentials (free from Microsoft.com) and I will use Malwarebytes to do additional malware scans in safe mod. I use a heck of a lot more tools for my removals but you can read about that stuff in the Tech Help section of our forums. If anyone should have questions about this stuff, I do it for a living and don't mind helping out. Visit me in the Tech Help forum or send me a PM as I try to log in at least once a day.
