Only open documents from trusted sources, and even in that case, it is still a good idea to scan the files with a virus scanning application. Another common type of virus is called a Trojan Horse. This type of virus is disguised as a useful program or joke program, but it actually releases a virus instead of doing what it claims to do. Don't start a program unless you know what it does, and even if it's from a trusted source, make sure you scan it first. Scanning a file only takes a moment, and it could save you and others from down time that can be better spent doing other things.
Viruses are very common, but virus prevention is also very advanced.
With the correct precautions and anti-virus software, most viruses can be neutralized before infesting your system and causing undo harm and hassle. However, Anti-virus software must be kept up to date. The latest versions of Microsoft Office have the ability to warn you of potential security risks. To enable this protection, you need to turn on macro virus protection, a feature that warns you when you try to open a document that contains macros that a possible security hazard exists. You can then turn off the macro features and view the document in a safer environment.