Problem with XDMCP and an account of domain

[EXT / EUREKA LE CUNFF Laurent]

Hello, 
I use Cygwin in XDMCP to connect me to a station HP/COMPAQ OSF.40. I am
under NT 4.0 SP6. 
When I use an account local under Windows I obtain the screen of login of
the distant station into 2 or 3 seconds. 
With an account of domain this time passes to 40 seconds. Can you provide me
tracks concerning this problem.
 Thank you in advance.