Does it have Internet connection? If so, it is probably running something you don't want it to.
You are probably loaded up with SpyWare/Malware or possibly even a virus. Check your virus status first.
If you are unfamiliar with spyware/Malware, check out the articles at:
http://www.pcmag.com/article2/0,4149,1522416,00.asp
http://www.pcmag.com/article2/0,4149,1523357,00.asp
A good program to use if your Windows Viruscanner is compromised is either NOD32 for DOS trial at:
http://www.nod32.com/download/trial.htm
Or Mcafee's Stinger at:
http://vil.nai.com/vil/stinger/
After you are virus free then attack SpyWare.
For the Spyware/Malware the two best Free scanners are AdAware SE at:
http://www.lavasoftusa.com/
And Spybot Search & Destroy version 1.3 at:
http://www.safer-networking.org/index.php?page=download
After Installing each check for updates before proceeding. Both have several cool tricks, Adaware has a custom search that can search your Hosts file and your archived files as well. SPpybot S&D has an new program called Teatime that doesn't install by default you have to check the box when you are installing. SPybot S&D also has an Immunization program.
Another excellent program is SpySweeper from www.webroot.com, it allows for one update and then you need to purchase to get anymore updates. It will find a lot that the two free one didn't.
I also use PestPatrol which also costs money. It is located at:
http://www.pestpatrol.com/ and they have a free pest scan if you can stay on the Internet long enough.
Steve Gibson also has several really good security tools as well as his famous "Shields UP" tester at:
www.grc.com
When you are all clean, get the free ZoneAlarm 4.5 at:
http://download.zonelabs.com/bin/free/1043_zl/zapSetup_45_594_000.exe