domain scan i V5

I can't get the domain scan to work in v5, this is just xp2 sp2 computers.
If I install the v4 it works fine, I have changed the "Allow remote administration exception"
Like a say, it works in v4 but not in v5.
If I turn the firewall off in the xp computers it works, but this is not an option.

Any Idea`?

Regards
Daniel