Function Discovery Resource Publication

Hello,
I have Windows Vista Ultimate and two other XP computers. The two XP's are
communicationg through the network (workgroup).
The problem is the my Vista computer cannot communicate with the XP ones. I
have tried to install the LLTD, with no luck. I can see those computers in
the network map, but I cannot share files or printers.
In the Network and Sharing center, I have file sharing, public folder
sharing, password protected sharing and media sharing ON. for some reason, I
can't switch the Network Discovery from custom to ON. I looked at Windows
Help, and I saw that dnscache, fdrespub, ssdpsrv, and upnphost services have
to be started.
For some reason, when I look in the "Services" tab in Task Manager,
dnscache, ssdpsrv, and upnphost services are running, and only the FDResPub
(Function Discovery Resource Publication) service is stopped. When I try to
start it, I get two types of error messages:
1. "The operation cpuld not be completed. Access is denied."
2. Windows could not start the Function Discovery Resource Publication
service on Local Computer. Error 0x80070001: Incorrect function.

My user is an Administrator.
How can I cause the FDResPub service to run??

Thank you in advance,
Amity