This fix is mentioned in a couple of the following links.
"To resolve this problem, reinstall SP1 for Windows XP. If
you cannot reinstall SP1, start Registry Editor, and then
locate the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\RasMa
n
Export the RasMan subkey as exported rasman key. To undo
the editing of this registry key, double-click
the "Exported rasman key.reg" file that you just saved.
Note the Data value for the ObjectName item. If this
value is not LocalSystem, modify the ObjectName item to
change the value data to LocalSystem. Locate the
following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\RasMa
n\PPP\EAP
Delete the following registry keys under the EAP subkey:
25
26
Quit Registry Editor, and then restart your computer."