Question : Help resolving error code 633 for dial-up modem in Vista

I am working on a computer with Vista Basic and a dial-up connection and keep getting "Error 633: the modem (or other connecting device) is already in use or is not configured properly.    Using a modem which has been tested as good in another PC using the same phone line.  I have done the following to try and resolve this error, with no success:
1. Queried the modem through Device Manager and it returns Success and no errors.  
2. Changed the com port from 3 to 1 and 3 to 5 to see if the port is the problem.  
3. Checked to see if any programs are running that may be using the modem and have ended all processes except csrss.exe, winlogon.exe, rundll32.exe, ccsvchst.exe, dwm.exe, explorer.exe, taskmgr.exe (which cannot be closed).
4. Norton Internet Security 2008 is installed, and I've tried with and without every security setting disabled.
5. Re-installed the modem.
6. Removed and recreated the DUN connection.
7. Checked to see if any other communication program might be installed or running:
  a. ActiveSync - no
  b. Palm Sync - no
  c. Fax dialers or monitors - no
  d. 3rd party dialers - no
8. Tried resetting TCP/IP using the netsh command.

I'm stumped.  Anyone have any suggestions?

Daimeion

Answer : Help resolving error code 633 for dial-up modem in Vista

Looks like nobody has a solution, so I resorted to a Factory Restore, which restored the original factory installation of the OS.  The computer now dials-up correctly.  It appears that the problem was an OS issue of some kind, because it works perfectly now.  If anyone has any ideas what it might be, I'd love to hear about it.  Otherwise, my solutions seems to be the only resort.