Win XP's Universal Plug and Play Device Host service starts and thenstops immediately

It's the wierdest thing, I noticed today that my UPNPhost service is
no
longer working on two of my XP machines. I noticed it on my desktop
first, so I went to my laptop to compare, and found out that it's not
working there either! I've checked through a number of webpages and
none
of them have had the solution for me yet.

So I'll go through what I've already done.

(1) The upnphost service was not working, so I tried to re-enable it
in
the services manager. I made sure that it's dependent services were
also
running (and set to automatic), SSDP and HTTP. The following message
popped-up after the attempted startup:

"The Universal Plug and Play Device Host service on local computer
started and then stopped. Some services stop automatically if they
have
no work to do, for example, the Performance Logs and Alerts service."

(2) I then went to see if the XP firewall was blocking the UPnP
Framework. It wasn't, it's listed within its exceptions list.

(3) Another article suggested that the problem might lie in the
registry, it suggested that I go into regedit and make sure that the
"Local Service" user account have full control permissions over the
following key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\UPnP Device Host

The permissions were already set properly. This was suggested in the
following article:
http://www.microsoft.com/communities...94d8d53014&p=1

(4) I then went and tried to uninstall and reinstall the UPNP services
in Add/Remove Programs. This made no difference.

(5) I got stumped, and came here for help. :-)

Yousuf Khan