Over the last 3 years the most frequent support call that I receive is from people who have noticed that over time their computer has gotten really slow. There are a number of things that can really slow your computer down, and some of them are very easy and simple to track down and fix.

If you notice a dramatic slowdown right after you install a new program, then that program is the likely cause. It could be poorly written or have a bug or it could just be conflicting with something else on your system. For instance, if you have one antivirus program installed and you install a second one, you will likely notice a slowdown along with other problems. This doesn't mean that the second antivirus program has a problem. It is simply conflicting with the first one. It is not a good idea to run two antivirus programs because they will cause problems like your system freezing up when they both try to scan the same file.

Another good thing to check if the slowdown is sudden is your internet connection speed. Another sign of this would be when the computer itself still seems quick - logging in, opening a Word Document, etc. but anything you do on the internet is slow - visiting a website, checking email, etc. One way to test this is to run a speed test and see how it compares to the speed advertised by your internet service provider. A couple of my favorite sites for speed tests are http://www.speedtest.net and http://www.dslreports.com

Unfortunately, one of the hardest problems to deal with and the one I see the most often is when a computer has become infected with malware. This usually results in a gradual slowdown that you don't notice at first. It may also result in strange error messages or an increased number of pop-up advertisements.

There are a lot of misconceptions about malware, and many of you may not have heard that term or may have a vague idea what it means. So I am going to start a series of articles today with some information on what malware is and why it causes problems. Later I will post some information on how systems get infected by malware and what steps you can take to protect your computer.

Malware is a generic term that encompasses a number of different, mostly malicious, types of software. It allows us to discuss the whole range without being specific because for the most part if you are experiencing a problem you don't care whether it is a virus, worm, or spyware, you just want it gone and for your computer to work normally again. However, it is a good idea to have a general idea of what you are facing and where it comes from in order to know what you need to do to protect yourself. This is where things get a little difficult. I could easily write 2 or 3 pages of technical definitions on the differences between a virus and a piece of adware. However, that would bore both of us senseless. Hopefully, I can instead give you a mildly interesting wide overview, that while somewhat technically incomplete, will give you the basic information you need.

Viruses are the old demon. They are certainly still around and a threat, but they are nothing compared to the new generation of problems you can face. Viruses are the destructive teenager that lives down the street. Like your neighborhood juvenile delinquent, they may do something that is only as mildly irritating as ringing your doorbell and taking off running. On your computer this could be a virus that does nothing but spread itself to as many computers as possible. Or maybe it pops up a message on your screen occasionally.

Maybe later that unruly teenager graduates to spray painting graffiti everywhere- this could be something like renaming a bunch of your files.

If you are really unlucky you could live near someone in a hurry to get to prison. Maybe your friendly neighborhood delinquent has discovered smashing windows or even pipe-bombs. That is to say deleting system files so your computer won't boot, or even actually deleting your pictures and documents.

What these things all have in common is that they are unoriginal pointless acts of destruction. Mostly they can be easily stopped by installing a good antivirus program and keeping it current. Sure, over time viruses have gotten smarter. Just like our neighborhood example eventually learns to undertake their pranks under the cover of darkness instead of the middle of the day. Viruses learn new tricks to hide themselves and slip past your antivirus software. That is why keeping it updated is so important. The goal is usually nothing more than gaining attention. Maybe the author just likes to see the news articles about the trouble they created, or maybe they do it to win points with their circle of friends.

That is the real difference between simple viruses and the new generation of threats. Unlike viruses, most other malware is driven by money. That is what makes it so dangerous. This stuff is more like the professional con artist. It may not be readily apparent that something is wrong. Sometimes it will be disguised as something that is free or included with something that is free. More often lately, it will be something you have to pay for. Scam artists have known this trick for years. If you spend money on something then psychologically it is good and has value. Be extremely concerned about anything that tells you your computer has a problem but that if you buy this software it can fix it for you. Most of the best tools available to fix malware problems are free.

Malware is getting better and better at hiding itself. Sometimes you won't notice it until you have many infections and the combined effect is to slow your computer to a crawl. Some programs look for their competitors and remove them before infecting your computer to try and keep you from noticing the slowdown. The real problem, however, lies in what this software does.

The most innocuous malware tries to earn the authors money by subjecting you to ads. Sometimes these are popup ads, sometimes they appear to be system messages. Many times your browser is just broken so that you are always redirected to a page of ads when you open it, or the software replaces parts of legitimate sites with ads.

A step up from that is malware that actually lets the author take over your computer. This allows them to use your computer to infect other machines, launch attacks against businesses or websites, or simply install more malware that they want you to have.

If you remember that I said this is about money then you may be wondering how this gets the author money. The answer is that through the malware they can take control of thousands of machines. They then rent these machines out to other people to perform the tasks I mentioned. They can also use your computer as a file server and fill up the drive with illegal software or music that they want to make available to other people without associating it with themselves.

The worst and most dangerous malware is after you. Fortunately, this is still a very small percentage of malware, but that is changing. The most dangerous malware can actually track everything you do and every key that you type. They do this to capture your credit card number when you order something on line, or you bank account number and login information when you visit your bank online. As I said this is a very small percentage of the malware in the world today. It is usually targeted in ways that will provide the highest return. In other words this is usually intentionally installed on computers the public will be using - the business center at a hotel, the internet cafe down the street, etc. This is done without the owner of the computers ever knowing, which makes it absolutely critical that you never visit your bank, make an online purchase, or do anything else that involves signing into a site or using your credentials when you are using a publicly accessible computer.

Also, don't be fooled into thinking that you are safe. Just because a place is a large chain and has new sophisticated equipment doesn't make them immune. Additionally, just because an internet cafe is in a small town and only has a couple of old machines doesn't make it safe. The last tourist to walk in before you may have been hoping to let everyone who comes in after him pay for his next vacation.

Keep watching for my follow up articles on what to do if you suspect your computer has malware, and how to protect your computer to help avoid malware.