If your PC has not been infected by Malware, it is almost certain that you know someone who has had this horribly frustrating experience.

I have disinfected a lot of clients’ PCs. As a result, I have some thoughts on their experiences you might find useful:

• This may sound elementary, but buy a good anti-virus/anti-malware product.  The ones you get free usually won’t protect you from much.  Some may even cause your PC to become infected.
• As if to contradict the first paragraph, if your ISP (Internet Service Provider) provides an anti-virus/anti-malware product as a benefit of subscribing, use it.  Comcast provides “Norton Security Suite”  for up to 7 computers included in residential Internet subscriptions.
• Be sure to keep your operating system up-to-date.  Microsoft supplies frequent security updates for all of its actively supported products.  Keep your updates up to date.
• Keep your anti-virus/anti-malware software up to date.  Many paid licenses have to be renewed periodically.  If you let your anti-virus/anti-malware license expire, you are not adequately protected.
• Only download software from the owner’s site.  If you do a Google search on “Adobe Reader”  you will find many listings.  The top listings on this search are not the official Adobe web site.  In fact, you don’t see “www.adobe.com” until the fourth listing.  The others will send you an adulterated copy of Adobe reader.  Many will contain an unexpected payload of something as simple as a tool bar, or as malicious as the “Conduit” virus.  Always download from the vendor’s own site.
• If your PC starts displaying unexpected pop-ups, or your browser’s address bar doesn’t take you to the site you’re expecting, stop clicking on things.  You will only worsen the infection.  The pop-ups will usually warn you of an infection and ask you to click on a link.  At the link, you will find what looks to be the solution to your problem, so you download it.  This usually magnifies the infection.  Your only practical solution is to buy a new computer or have your current computer repaired.  If you buy a new one, you will probably repeat the behavior that caused the infection in the first place.  If you get it repaired, you will probably get a bunch of additional services:  disinfection of your PC, installation of all Microsoft security updates, optimization of your PC to improve performance and a brief tutorial on how to avoid the problem in the future.
• If this is the first piece of software you’re installing from a vendor, read their license agreement … really.  If you don’t like it, don’t use it. See this South Park episode on the perils of blindly agreeing to license agreements without reading them.
• Have at least two user ids on your PC.  One user id should be for the administrator and should have a secure password.  The other(s) should be for standard users.  The difference is that the standard users cannot install software.  When they want to install something new on a shared PC, they will have to get the administrator’s okay (and password).  When a malicious web site tries to sneak something in, it will likely be prevented by the administrator.

I hope you find these suggestions useful and that they contribute to your infection-free computing.