DCDiag results question

So I tried to add a windows XP machine to a Windows 2000 server. But get the
error:

"A Domain Controller for the Domain XXX could not be contacted"

so then I run the DcDiag.exe file and the following test fails:

FsmoCheck
Warniing: DcGetDcName <Pdc_Required> call failed, Error 1355
A Primary Domain Controller could not be located.
The server holding the PDC role is down.

So my question is pretty basic... Where should I go from here to fix this?
Any help is much appreciated.
TIA