VPN pptp

I have then installed webmin, configured the pptp
tunneling, but when I click on "connect" button, I have the following
messages:

QUOTE
Apr 28 23:05:34 Socrates pptp[6404]: anon
log[pptp_dispatch_ctrl_packet:pptp_ctrl.c:759]: Outgoing call
established (call ID 0, peer's call ID 0).
Apr 28 23:05:35 Socrates kernel: usb-uhci.c: process_transfer: fixed toggle
Apr 28 23:05:36 Socrates pptp[6411]: anon
warn[decaps_hdlc:pptp_gre.c:209]: short read (-1): Input/output error
Apr 28 23:05:36 Socrates pptp[6411]: anon
warn[decaps_hdlc:pptp_gre.c:210]: pppd may have shutdown, see pppd log
Apr 28 23:05:36 Socrates pptp[6404]: anon
log[callmgr_main:pptp_callmgr.c:236]: Closing connection
Apr 28 23:05:36 Socrates pptp[6404]: anon
log[pptp_conn_close:pptp_ctrl.c:357]: Closing PPTP connection
Apr 28 23:05:36 Socrates kernel: usb-uhci.c: process_transfer: fixed toggle
Apr 28 23:05:37 Socrates kernel: usb-uhci.c: process_transfer: fixed toggle
Apr 28 23:05:38 Socrates pptp[6404]: anon
log[call_callback:pptp_callmgr.c:76]: Closing connection
Apr 28 23:05:39 Socrates kernel: usb-uhci.c: process_transfer: fixed toggle
UNQUOTE

Does anybody know the meaning? Wht's happening?