I disabled LCP it in the properties of the XP network connection for the vpn
Really? Are you sure you didn't disable 'LCP extensions'? LCP is necessary:
http://www.ietf.org/rfc/rfc1548.txt Link Control Protocol
In order to be sufficiently versatile to be portable to a wide
variety of environments, PPP provides a Link Control Protocol
(LCP). The LCP is used to automatically agree upon the
encapsulation format options, handle varying limits on sizes of
packets, authenticate the identity of its peer on the link,
determine when a link is functioning properly and when it is
defunct, detect a looped-back link and other common
misconfiguration errors, and terminate the link.