Slow computer, random shutdowns, buggy mouse... Urgh must be a virus! Most of us have probably experienced a computer virus in one form or another; however, not all viruses are created equal.

Most can be sorted with a quick clean-up and an update of your anti-virus – others, though, can spread like wildfire, cause billions of dollars worth of damage, and even be compared to a weapon of mass destruction.

In today's video, we look at 5 of the most costly computer viruses ever.