1.Be infected with Spyware, or Adware. (Spyware/Adware is a program usually disguised as helpful utilites such as search tools, memory managers, internet optimizers, time and date utilities, and ironically antispyware programs.)
2.Be infected with a virus.
3. Have to many programs starting at one time.
4. Not have enough memory.
5. Be really old and decrepit and need an upgrade.
Solution: First run the Microsoft Configuration Utilitie. Go to Start, Run, and type msconfig in the box and click OK. Next, click the box marked startup in the upper right corner and uncheck all the boxes except antivirus. (you will have to read the info in the box next each item to determine what it is, ccApp is norton antivirus for example because I can see symantec over to the right.) A great site for determining what startup items are necessary or useful is
you can look up whatever items you are curious about before you disable it, dont worry, can turn anything you like back on by doing the same thing over later, but the only thing I recommend leaving on is antivirus, and antispyware programs. Restart the computer when asked, then put a check mark in the box, dont show me this message again when it warns you you've used the configutation utility. Run your antivirus and download
from Lavasoft and run the program. Remove anything found after the scan by putting a check mark in the box beside the items. If the computer is still slow after these steps you may need to add more memory. Bring it in for a free estimate.