You cannot create a network connection after you restore Windows XP

1. Click Start, and then click Run.

2. In the Open box, type regedit, and then click OK.

3. Locate and then click the following key in the registry:
HKEY_LOCAL_MACHINE >> SYSTEM >> CurrentControlSet >> Services >> RasMan >> PPP >> EAP >> 25

HKEY_LOCAL_MACHINE >> SYSTEM >> CurrentControlSet >> Services >> RasMan >> PPP >> EAP >> 26

4.On the Left hand side you will see a Folder 25 and 26 just right click on it and click on delete
5.Quit registry editor, and then restart your computer.
For More info click on the link below
http://support.microsoft.com/kb/329441