Do not use more than one anti-virus program

[MikePeller]

Don't use more than one antivirus program

It's vital to protect your computer with appropriate security software. But running two antivirus programs on your computer – for example, running Microsoft windows 8 Security, which comes free with Windows, and then installing an extra antivirus program from a company such as McAfee or Norton – can cause conflicts on your computer. This can make your computer sluggish and at worst can cause computer crashes.

If you have two different antivirus programs installed on your computer, make sure only one of them is active.