14. Mac malware
No matter what you've heard, Macs are not immune to security problems, including malware that employs deceptive techniques to fool users into installing it.
If you use a Mac, don't sit back and assume it's impregnable. It's not. You need to keep up to date with security updates just the same as Windows users. Things to watch out for include the automatic updates that Apple releases, as well as the various patches for software that third-party vendors may not automatically alert you to.
15. Fake antimalware
Fraudulently advertised, ineffective antimalware ranks among the fastest-growing types of online scams. Online ads that simulate Windows alert messages tout products such as DriveCleaner, WinFixer, Antivirus XP and Antivirus 2009, warning you that your PC is infected with malware and advising you to buy the named product to fix it.
Some purveyors of these sham utilities embed warning messages directly into the Windows desktop or pop-up messages from a System Tray applet to convince you the problem is serious.
But these scareware tools only pretend to scan your computer for dangerous malware. Instead, they detect either innocuous, commonly used Registry keys or non-existent (or planted) alien files.
Even worse, many of the programs disable key components of Windows, such as the Registry editor or Task Manager.
Or they may deactivate options within the OS's Display Properties settings to prevent you from killing the programs or removing the alert messages.
People are particularly susceptible to these packages because the sneaky sellers charge an apparently reasonable fee.
A legitimate malware remover - one that independent testing has determined is effective - should be able to take care of the immediate problem of having an adware program that refused to be uninstalled. Check your security software to see if it will do the trick.
But the real fix for this plague may be concerted government action. Late last year the US Federal Trade Commission asked a federal court to step in and thwart some perpetrators of this type of scam. It may be that prison terms or massive fines are the only useful deterrents, and will have to be introduce here too.