It does sound like your computer is exhibiting signs of being infected. It may be too late to try to install software to remove the infection, depending on what it is.
Of course, I don't know if this is true in your case, but sometimes kids download music from sites that send them infections. Or, they get music from their freinds that is infected because of where the friend got the music from. At least that is a main source of infection.
Once you get one piece of malicious software on the computer, then you usually get several more until the computer barely works anymore as all of the resources are eaten up by a lot of crummy software running on your computer, and it no longer will do the work that you bought the computer to do in the first place.
Your options are:
Back up all of your data and then wipe out the hard drive and reinstall windows.
Or, you can get help from the folks in the High Jack This forum for help in removing the infections, or at least in diagnosing what infections you have.
Please let us know if you decide to wipe out the data on the hard drive (btw, formatting is not enough!) and we can walk you through this step by step.
Or, for help with removing your infection I would like to refer you to the Highjack This (HJT) forum here at BleepingComputer.com: First:
Read the Preparation Guide found HERE
. It is very important
that you follow ALL of the instructions found within. (There are many important steps in this guide that may clean your computer.) Second:
Post your system information along with a brief description of the problems you are having, and your HJT log in the HJT forum found HERE
NOTE: Please, after you post your HJT log DO NOT make another post in the HJT forum until it has been responded to by a member of the HJT Team. The first thing they look for, when looking for logs to reply to, is 0 replies. If you make another post there will be 1 reply. The team member glancing over the replies might think someone is already helping you out and will not respond. So, just make your post and let it sit there until a team member responds. The volunteers who work that forum are very busy, so please be patient and wait for a response. It can sometimes take a few days.Third:
If, after finishing your work with the folks at the HJT forum you have issues with XP related to the removal of the infection, then come back in here and let us help you get your computer back to normal.
You are in good hands! Good luck!