VPN+PPTP+ Win2003+XP three minutes only ...

Hello!

I have problem with vpn connection. There are two vpn clients. One of
them have a stable connection and the second have only three minutes
connection. They use win xp sp2 system. They use two diffrent ISP.
I turned on debuggin and loggin on RAS and:
(connection: 19.30, tree minutes idle, 19.33 self disconnecting)

PPP.LOG
[3764] 10-28 19:30:33:759: Line up event occurred on port 134
< ..............>
[3764] 10-28 19:30:35:571: AuthAttribute SessionTimeout = 0
[3648] 10-28 19:33:40:758: PPPEMSG_LineDown recvd, hPort=134
<...............>

RASAUTH.LOG
[1232] 19:30:34:337: RasAuthProviderAuthenticateUser called
<...............>
[1232] 19:30:35:571: IASResponse = 4, FailureReason = 0x0
[5544] 19:33:42:757: RasStopAccounting called

RASMAN.LOG
[3648] 10-28 19:30:33:634: WorkerThread: Async work event signaled on
port: VPN4-127
<................>
[3648] 10-28 19:33:40:758: WorkerThread: Disconnect event signaled on
port: VPN4-127
[3648] 10-28 19:33:40:758: OVEVT_DEV_STATECHANGE. pOverlapped =
0x2a62b90
[3648] 10-28 19:33:40:758:
d:\srvrtm\net\rras\ras\rasman\rasman\worker.c, 1995: Disconnecting port
134, connection 0x0, reason 1
[3648] 10-28 19:33:40:758: Disconnecting Port 0xVPN4-127, reason 1

IGMPv2.LOG
[1108] 19:30:29: Entering _WT_ProcessTimerEvent()
<...................>
[1232] 19:32:40: In _DebugCheckLowTimer
[1216] 19:33:42: Entering DisconnectRasClient for IfIndex(10002),
NextHop(10.10.10.248)
[5544] 19:33:42: Entering WF_ProcessProxyAlert()

TAPI23.LOG
[3736] 19:30:33:634: [INFO ] AsyncEventsThread: msg=23, hDev=x103db,
p1=x0, p2=x10242, p3=x4
<........................>
[3736] 19:33:40:758: [INFO ] AsyncEventsThread: msg=2, hDev=x10242,
p1=x4000, p2=x0, p3=x0
[3736] 19:33:40:758: [INFO ] AsyncEventsThread: posting msg,
hwnd=x100e4
[3672] 19:33:40:758: [TRACE] TAPIWndProc: received WM_ASYNCEVENT,
hwnd=x000100E4
[3672] 19:33:40:758: [INFO ] Calling app's callback, hDev=x10242,
Msg=2, dwInst=x1477a8 P1=x4000, P2=x0 P3=x0

ROUTER.LOG
[1232] 10-28 19:30:32:180: RouterIdentityObjectOpen returned 0
<.........>
[1216] 10-28 19:33:40:758: Rasman state change received from port 134,
2->4
[1216] 10-28 19:33:40:758: SvDevDisconnected:Entered, hPort=134

KMDDSP.LOG
[3720] 19:30:33:634: ! AsyncEventsThread: got a line event
<.........>
[3720] 19:33:40:758: ! AsyncEventsThread: got a line event
[3720] 19:33:40:758: ! ProcessEvent: event(000A87C8), msg(2),
ht_line(00BC0000), ht_call(8000009B), p1(00004000), p2(00000000),
p3(00000100)
[3720] 19:33:40:758: ! PE::fnLineEvent(CALLSTATE): htline(0001001E),
htcall(00010052), p1(00004000), p2(00000000), p3(00000100)
[3720] 19:33:40:758: ! PE::fnLineEvent(CALLSTATE_IDLE):
htline(0001001E), htcall(00010052), p3(00000100)
[1936] 19:33:40:758: lineGetCallStatus(66): call(00C00006)
[1936] 19:33:40:758: ! SyncDriverRequest: oid(GetCallStatus), devID(1),
reqID(367), hdCall(000071E8)
[3628] 19:33:40:758: lineDrop(93): reqID(101a8), call(00C00006)
[3628] 19:33:40:758: ! AsyncDriverRequest: oid(Drop), devID(1),
ReqID(101a8), reqID(368), hdCall(71e8)