First be sure to get all the latest security updates and patches for your Windows operating system directly from Microsoft. Second run a good firewall particularly if you have an always on broadband connection or wireless system. Have a frequently updated anti-virus progam running--I'd stick with one of the two major ones. Third, use a reliable spyware remover weekly. Ad-Aware and Spy-bot Search and Destroy are both free, don't add any spyware themselves and available for simple download
If you get stricken with the about:blank CWS variant horror, you will be scouring the web for online fixes too. LOL!
The Windows updates/patches and firewalls are useless to stop it. Ad-Aware and SpyBot S&D are useless to remove it. Each one will find some components (though not all - and not the same ones between them) but they will come right back.
The only way to get rid of it is to corner the hidden .dll reloader file, and that's borderline impossible to do when Windows is running.