Netlogon service dont start

Hi

(I'm going to try to explain my problem, but i'm french and my english is poor)

Architecture:
Server WSM on a Dell PE860, 8Go Ram and two hard disks SSD on raid0
Windows server 2008r2
Microsoft SQL express 2008
WSM 4.1.0

Network 1Gb from WSM server to main switch (Cisco 3560G-24)
Etherchannel link between main switch and secondary switch
Network in 100 mb between secondary switch (Cisco 2960-24TT) and Z00d clients

Ten Z00d client with XP SP3
Antivirus Symantec Endpoint 11 on client
Active Directory actived
and a GPO to have network drives automatically (net use....)

When i boot on a device, shared mode and volatile cache, the Netlogon service dont start
I have to log on an administrator session and manually active the service
without this service, the GPO dont work
I try on the reference device in private mode, it's the same problem
I try also on the reference device, I boot on the local disk, the service work properly
(this disk was used to built the OS image)

the Netlogon service depend of the OSMclient service....

I dont understand why the netlogon service dont start automatically

JD