My virtual modem does't disappear in RAS's ports

I have a problem with my virtual modem driver. My modem is PnP device
based on Toaster and Fakemodem samples.
Virtual modem does’t disappear in RAS’s ports when i remove this
modem (unplug this modem). Also after that hyperterminal hangs up when
i click on “Properties” toolbar button. This bug may be reproduced
only on several computers in our office.

Can anyone tell me possible reasons of this situation?

I beleave the reason may be one from these points:

  • Some IRPs were not completed.
  • WMI support does not uninstalled properly
  • May be some links in registry were not removed
  • ???

How does hyperterminal get the list of devices?
How does RAS get the list of ports?

Thank you.

with best regards,