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.