1)Spyware is on your system. Like it or not, statistically speaking, you probably have spyware on your machine right now. There are so many malicious programs floating around out there that one or two have bound to have gotten past all of your security settings. McAfee and Norton Anti Virus are both excellent programs, but even they can be beaten by the determined spyware makers and distributors. One recent computer repair man said, close to 80% of the machines that he services have spyware on them. I believe it. Spyware can be sneaky and it can install quietly without your knowledge. Your system probably has spyware on it; make sure it doesn't corrupt your data files or worse.

2)Spyware attacks through certain programs. One program that seems to have been a magnet for spyware on my machine has been my browser (one that is distributed by a major computer comapany). Maybe I didn't update my security settings or maybe they were not strong enough but somehow, somewhere, my previous browser seems to have been vulnerable to spyware attacks. Switching to an open source browser (FireFox) was like night and day. Firefox hasn't seemed to let any spyware install itself so far. I switched about 6 months ago. If you haven't tried Firefox, you might consider downloading a trial copy.

3)You need to get some form of protection against spyware. There are all sorts of companies out there claiming to have the magic cure for spyware. Some work fantastically, some don't work as well. Finding the spyware removal silver bullet isn't as hard as it seems, but it does take some work and a little bit of research. I use several programs on my new machine that I am typing this on. The hardest part is getting spyware off of your machine once it is installed, so you don't want it to get on your machine to begin with. Using the right type of browser (as mentioned above) is one of the best ways to insure you don't have to spend a lot of time cleaning your machine.