Modem izgublja povezavo

Imam ISDN Pro TA modem. Pred dnevi se mi je začelo dogajati, da modem izgubi povezavo - ugasne se led za linijo (B1). Ikona za vzpostavljeno povezavo v systraju pa ostane. Če nato prekinem povezavo, računalnik nekaj časa zelo počasi dela. Če poskušam ponovno vzpostaviti povezavo, mi vse zablokira in pomaga samo reset. Če v lastnostih modema zaženem diagnostiko, dobim sporočilo, da vrat ni možno odpreti. Tako pomaga samo ponovni zagon, ki pa prav tako traja dalj časa.
Problem sem poskusil rešiti z ponovno instalacijo gonilnikov za modem, ki pa ni pomagala. Prav tako sem ponovno instaliral WIN98SE, pa ni nič boljše.
Problem se pojavlja tako na Siolu kot na Volji.
V log datoteki modema sem zasledil warnig napako zato prilagam izpis iz te datoteke :

11-10-2002 22:23:55.95 - 3Com USR ISDN Pro TA-S USB in use.
11-10-2002 22:23:55.95 - Modem type: 3Com USR ISDN Pro TA-S USB
11-10-2002 22:23:55.95 - Modem inf path: 3COMIMDM.INF
11-10-2002 22:23:55.95 - Modem inf section: ComPort.Install.2
11-10-2002 22:23:56.04 - 115200,N,8,1
11-10-2002 22:23:56.07 - 230400,N,8,1
11-10-2002 22:23:56.08 - 230400,N,8,1
11-10-2002 22:23:56.08 - Initializing modem.
11-10-2002 22:23:56.09 - Send: AT
11-10-2002 22:23:56.26 - Recv: OK
11-10-2002 22:23:56.26 - Interpreted response: Ok
11-10-2002 22:23:56.26 - Send: AT&F1E0Q0V1&A3&C1&D2S0=0
11-10-2002 22:23:56.44 - Recv: OK
11-10-2002 22:23:56.44 - Interpreted response: Ok
11-10-2002 22:23:56.44 - Send: ATS19=0&H1&R2&I0
11-10-2002 22:23:56.61 - Recv: OK
11-10-2002 22:23:56.61 - Interpreted response: Ok
11-10-2002 22:23:56.61 - Dialing.
11-10-2002 22:23:56.61 - Send: ATD#########
11-10-2002 22:23:57.52 - Recv: CONNECT 128000
11-10-2002 22:23:57.52 - Interpreted response: Connect
11-10-2002 22:23:57.52 - Connection established at 128000bps.
11-10-2002 22:23:57.52 - Error-control off or unknown.
11-10-2002 22:23:57.52 - Data compression off or unknown.
11-10-2002 22:35:28.45 - Hanging up the modem.
11-10-2002 22:35:28.45 - Hardware hangup by lowering DTR.
11-10-2002 22:35:39.86 - WARNING: The modem did not respond to lowering DTR. Trying software hangup...
11-10-2002 22:35:39.86 - Send: +++
11-10-2002 22:35:41.86 - ERROR: Unable to send command to the device.
11-10-2002 22:35:53.12 - Session Statistics:
11-10-2002 22:35:53.12 - Reads : 600693 bytes
11-10-2002 22:35:53.12 - Writes: 136199 bytes
11-10-2002 22:35:53.12 - 3Com USR ISDN Pro TA-S USB closed.

In se konfiguracija :
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AMD Athlon TB 1000
HD IBM 40 GB 7200
GeForce2 MX 400 64 MB TV out