Thanks for the suggested tests. I find that text to speech works (I created/synthsised a new OGM which played back without crashing). I deselected both caller ID notifications (screen & speakers). If I call to that line the modem answers the call but the caller hears nothing. The mouse pointer still moves but indicates "in progress" (on my PC it's the circle). Nothing else works (no icons/applications/buttons respond). There is disk activity. Ctrl-Alt-Del does nothing. I still have to hold the power button until power down. The IVM call log ends with "22:11:46 IVM Answering Attendant Run". The modem log is:
06-17-2009 22:12:33.616 - File: C:\Windows\system32\tapisrv.dll, Version 6.0.6001
06-17-2009 22:12:33.651 - File: C:\Windows\system32\unimdm.tsp, Version 6.0.6001
06-17-2009 22:12:33.651 - File: C:\Windows\system32\unimdmat.dll, Version 6.0.6000
06-17-2009 22:12:33.651 - File: C:\Windows\system32\uniplat.dll, Version 6.0.6000
06-17-2009 22:12:33.676 - File: C:\Windows\system32\drivers\modem.sys, Version 6.0.6001
06-17-2009 22:12:33.746 - File: C:\Windows\system32\modemui.dll, Version 6.0.6001
06-17-2009 22:12:33.851 - File: C:\Windows\system32\mdminst.dll, Version 6.0.6001
06-17-2009 22:12:33.851 - Modem type: USRobotics V.92 Voice Win Int
06-17-2009 22:12:33.851 - Modem inf path: oem66.inf
06-17-2009 22:12:33.851 - Modem inf section: Modem1807_Vista
06-17-2009 22:12:33.851 - Matching hardware ID: pci\ven_12b9&dev_1007&subsys_00c412b9&rev_00
06-17-2009 22:12:33.856 - 115200,8,N,1, ctsfl=1, rtsctl=2
06-17-2009 22:12:33.856 - Initializing modem.
06-17-2009 22:12:33.866 - Send: AT<cr>
06-17-2009 22:12:35.866 - Timed out waiting for response from modem
06-17-2009 22:12:35.866 - The modem failed to respond to the initialization command, Retrying one more time
06-17-2009 22:12:35.866 - 115200,8,N,1, ctsfl=1, rtsctl=2
06-17-2009 22:12:35.876 - Send: AT<cr>
06-17-2009 22:12:37.876 - Timed out waiting for response from modem
06-17-2009 22:12:37.876 - The modem failed to respond to the initialization command, Retrying one more time
06-17-2009 22:12:37.876 - 115200,8,N,1, ctsfl=1, rtsctl=2
06-17-2009 22:12:37.886 - Send: AT<cr>
06-17-2009 22:12:39.886 - Timed out waiting for response from modem
06-17-2009 22:12:39.886 - Session Statistics:
06-17-2009 22:12:39.886 - Reads : 0 bytes
06-17-2009 22:12:39.886 - Writes: 0 bytes