Seems to be the problem here, too.

Oct 27 11:22:27 nb-dschwan NetworkManager: <info>  Starting VPN service 'org.freedesktop.NetworkManager.pptp'... 
Oct 27 11:22:28 nb-dschwan NetworkManager: <info>  VPN service 'org.freedesktop.NetworkManager.pptp' started (org.freedesktop.NetworkManager.pptp), PID 10017 
Oct 27 11:22:28 nb-dschwan NetworkManager: <info>  VPN service 'org.freedesktop.NetworkManager.pptp' just appeared, activating connections 
Oct 27 11:22:28 nb-dschwan NetworkManager: <info>  VPN plugin state changed: 3 
Oct 27 11:22:28 nb-dschwan NetworkManager: <info>  VPN connection 'VPN-Verbindung 1' (Connect) reply received. 
Oct 27 11:22:28 nb-dschwan pppd[10018]: Plugin /usr/lib/pppd/2.4.4/nm-pptp-pppd-plugin.so loaded.
Oct 27 11:22:28 nb-dschwan pppd[10018]: pppd 2.4.4 started by root, uid 0
Oct 27 11:22:28 nb-dschwan pptp[10020]: nm-pptp-service-10017 log[main:pptp.c:314]: The synchronous pptp option is NOT activated 
Oct 27 11:22:28 nb-dschwan pppd[10018]: Using interface ppp0
Oct 27 11:22:28 nb-dschwan pppd[10018]: Connect: ppp0 <--> /dev/pts/1
Oct 27 11:22:28 nb-dschwan pptp[10027]: nm-pptp-service-10017 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 1 'Start-Control-Connection-Request' 
Oct 27 11:22:28 nb-dschwan pptp[10027]: nm-pptp-service-10017 log[ctrlp_disp:pptp_ctrl.c:739]: Received Start Control Connection Reply
Oct 27 11:22:28 nb-dschwan pptp[10027]: nm-pptp-service-10017 log[ctrlp_disp:pptp_ctrl.c:773]: Client connection established.
Oct 27 11:22:29 nb-dschwan pptp[10027]: nm-pptp-service-10017 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 7 'Outgoing-Call-Request' 
Oct 27 11:22:29 nb-dschwan pptp[10027]: nm-pptp-service-10017 log[ctrlp_disp:pptp_ctrl.c:858]: Received Outgoing Call Reply.
Oct 27 11:22:29 nb-dschwan pptp[10027]: nm-pptp-service-10017 log[ctrlp_disp:pptp_ctrl.c:897]: Outgoing call established (call ID 0, peer's call ID 47232). 
Oct 27 11:22:29 nb-dschwan pppd[10018]: MS-CHAP authentication failed: ^L^YM-iM-7M-|M-tM-^?M-?4M-aM-xM-7M-XM-vM-^?M-?chM-rM-7<M-kM-xM-74M-aM-xM-7<M-kM-xM-7M-^Zs^G^H
Oct 27 11:22:29 nb-dschwan pppd[10018]: CHAP authentication failed
Oct 27 11:22:29 nb-dschwan NetworkManager: <info>  VPN plugin failed: 1 
Oct 27 11:22:29 nb-dschwan pptp[10027]: nm-pptp-service-10017 log[pptp_read_some:pptp_ctrl.c:544]: read returned zero, peer has closed
Oct 27 11:22:29 nb-dschwan pptp[10027]: nm-pptp-service-10017 log[callmgr_main:pptp_callmgr.c:258]: Closing connection (shutdown)
Oct 27 11:22:29 nb-dschwan pptp[10027]: nm-pptp-service-10017 log[ctrlp_rep:pptp_ctrl.c:251]: Sent control packet type is 12 'Call-Clear-Request' 
Oct 27 11:22:29 nb-dschwan pptp[10027]: nm-pptp-service-10017 log[pptp_read_some:pptp_ctrl.c:544]: read returned zero, peer has closed
Oct 27 11:22:29 nb-dschwan pptp[10027]: nm-pptp-service-10017 log[call_callback:pptp_callmgr.c:79]: Closing connection (call state)
Oct 27 11:22:29 nb-dschwan pppd[10018]: Connection terminated.
Oct 27 11:22:29 nb-dschwan pppd[10018]: Exit.
Oct 27 11:22:29 nb-dschwan NetworkManager: <info>  VPN plugin state changed: 6 
Oct 27 11:22:29 nb-dschwan NetworkManager: <info>  VPN plugin state change reason: 0 
Oct 27 11:22:29 nb-dschwan NetworkManager: <WARN>  connection_state_changed(): Could not process the request because no VPN connection was active. 
Oct 27 11:22:29 nb-dschwan NetworkManager: <info>  Policy set 'Auto lit' (ath0) as default for routing and DNS. 
Oct 27 11:22:41 nb-dschwan NetworkManager: <debug> [1225102961.363015] ensure_killed(): waiting for vpn service pid 10017 to exit 
Oct 27 11:22:41 nb-dschwan NetworkManager: <debug> [1225102961.363273] ensure_killed(): vpn service pid 10017 cleaned up