It sounds like you have been infected with the Blaster Virus.
1) You need to enable the Firewall on the Dial-up connection before you
connect to the Internet again.
a. In Control Panel, double-click "Networking and Internet Connections", and
then click Network Connections.
b. Right-click the connection on which you would like to enable ICF, and
then click Properties.
c. On the Advanced tab, click the box to select the option to "Protect my
computer or network".
d. If you want to enable the use of some applications and services through
the firewall, you need to enable them by clicking the Settings button, and
then selecting the programs, protocols, and services to be enabled for the
ICF configuration.
283673 HOW TO: Enable or Disable Internet Connection Firewall in Windows XP
http://support.microsoft.com/?id=283673
2) Once you are connected to the Internet you should visit Windows Update
and install critical update KB833330 if it is listed as available, or
download the "Windows XP Professional and Windows XP Home Edition" version
of the fix from here:
http://support.microsoft.com/default.aspx?scid=kb;en-us;823980#WinXP
3) Download the Blaster Worm Removal Tool for Windows XP directly from the
Microsoft Download Center and install it
http://www.microsoft.com/downloads/...8b-fe98-493f-ad76-bf673a38b4cf&displaylang=en
4) Update your Anti-virus signature file and scan the entire system for
virus'.
5) If Windows Update shows you need numerous updates that you cannot
download over a modem you can contact the PCSafety line at (866) PC-SAFETY
and request a Windows Security Update CD.
129972 Computer viruses: description, prevention, and recovery
http://support.microsoft.com/?id=129972
826955 Virus Alert About the Blaster Worm and Its Variants
http://support.microsoft.com/?id=826955