spontaneous disconnects DFS shares w2k8

We just implemented a DFS (w2k8) within a windows 2003 domain. At first there
was no problem, now user experience spontaneous disconnects of their mapped
drivers (DFS).
When trying to reconnect from the propt with al "net use" it will state a
system 53 error.

When browsing to:
\\<server>\folder1\
I get an error, but when browsing to:
\\<server>\

I will see the shared folder and can browse them ??

Network monitor gives me the following result:

1236 20.578125 {NbtSS:12, TCP:11,
IPv4:0} 172.22.101.161 172.22.0.114 SMB SMB:C; Session Setup Andx, Krb5ApReq
(0x100)

1237 20.578125 172.22.101.161 172.22.0.114 ARP ARP:Response,
172.22.101.161 at 00-1A-4B-92-27-1F

1238 20.578125 172.22.0.114 172.22.101.161 ARP ARP:Request, 172.22.0.114
asks for 172.22.101.161

1239 20.578125 {NbtSS:12, TCP:11,
IPv4:0} 172.22.0.114 172.22.101.161 SMB SMB:R; Session Setup Andx, Krb5ApRep
(0x200)

1240 20.578125 {NbtSS:12, TCP:11,
IPv4:0} 172.22.101.161 172.22.0.114 SMB SMB:C; Tree Connect Andx, Path =
\\C-FS01-SH\IPC$, Service = ?????

1241 20.578125 {NbtSS:12, TCP:11,
IPv4:0} 172.22.0.114 172.22.101.161 SMB SMB:R; Tree Connect Andx, Service =
IPC

1242 20.578125 {SMB:127, NbtSS:12, TCP:11,
IPv4:0} 172.22.101.161 172.22.0.114 DFS DFS:Get DFS Referral Request,
FileName: \c-fs01-sh\zorgmh, MaxReferralLevel: 4

1243 20.578125 {SMB:127, NbtSS:12, TCP:11,
IPv4:0} 172.22.0.114 172.22.101.161 SMB SMB:R; Transact2, Get Dfs Referral -
NT Status: System - Error, Code = (549) STATUS_NOT_FOUND

1244 20.578125 {NbtSS:12, TCP:11,
IPv4:0} 172.22.101.161 172.22.0.114 SMB SMB:C; Tree Connect Andx, Path =
\\C-FS01-SH\ZORGMH, Service = ?????

1245 20.578125 {NbtSS:12, TCP:11,
IPv4:0} 172.22.0.114 172.22.101.161 SMB SMB:R; Tree Connect Andx - NT Status:
System - Error, Code = (204) STATUS_BAD_NETWORK_NAME

homedrives are not affected (same server, no DFS) . A normal ping will
resolve de fileserver? Clients are w2k, XP SP2 and SP3.
What is ruled out are so far:
virusscanner
firewall

Our DFS-servers (cluster) are running without any errors. If multiple users
have a specific drive mapped the disconnect is only on 1 client and not on
all connected clients. All users are within a regular LAN.
A reboot of the client will resolve de disconnect

Anyone any idea?

R. Wagter