You may not even know that your computer has been infected with spyware or adware until it slows your computer so much that some programs no longer work. Actually spyware is more of a common problem today than many viruses because they typically use social engineering to accomplish their task.
Spyware attaches itself to many so called "free" programs or offers that end users willingly download. Although not always malicious, spyware generally interrupts and slows down the computer to a crawl while bombarding the end user with pop-up ads or other programs than can log key strokes to harvest login IDs and passwords. You may try removing the spyware yourself.
To remove spyware you'll need to run two removal tools. Lavasoft's Ad-Aware and Spybot Search & Destroy will remove most spyware problems but they both should be run to completely remove as much spyware as possible from your computer. These programs are available at no charge. Ad-Aware SE Personal Edition 1.06 Spybot - Search & Destroy 1.4
Microsoft also has an AntiSpyware program at no charge. It is still in the testing stages. It can be downloaded here at no charge. Microsoft AntiSpyware (Beta) Tips and help on SpyWare from Microsoft Microsoft - How to prevent spyware.