samba - Mar 2008 - XP x64 will hang/bsod when using mapped network drive

Hi,

I have a very strange problem with a new Windows XP Professional x64
client machine which will either hang or BSOD when I manipulate (move,
copy, compress) a file on a mapped network drive BUT not when I navigate
to the file through My Network Places i.e. selecting WORKGROUP ->
FILESERVER -> Share2 -> Directory -> File.

I have a mix of Windows PCs on my network including Win2K, WinXP
(32-bit) which have all been using the accessing the shares without
problems for 18 months or so.  A new Vista Enterprise (64-bit) machine
was added at the same time as the XP 64-bit PC but it is just the XP Pro
64-bit PC that has this problem.  

I'm seeing many different Windows STOP codes but having tested all the
hardware components I'm satisfied that this is specicially something to
do with XP x64's interaction with Samba.

We are using RHEL4 which ships with Samba 3.0.25b.  The relevant
sections from smb.conf:

[global]
        netbios name = FILESERVER
        workgroup = WORKGROUP
        server string = File Server
        hosts allow = 1.2.3. 1.2.4. 127.
        load printers = no
        cups options = raw
        log file = /var/log/samba/%m.log
        max log size = 50
        security = user
        smb passwd file = /etc/samba/smbpasswd
        encrypt passwords = yes
        socket options = TCP_NODELAY SO_RCVBUF=65536 SO_SNDBUF=65536
IPTOS_LOWDELAY
        max xmit = 65536
        use sendfile = no
        lock spin time = 15
        lock spin count = 100
        oplocks = no
        level2 oplocks = no
        kernel oplocks = no
	  remote browse sync = 1.2.4.1
	  remote announce = 1.2.4.1/THEWORKGROUP
        local master = yes
	  os level = 34
        domain master = yes
        preferred master = yes
        wins support = yes
        dns proxy = yes
        preserve case = yes
        idmap uid = 16777216-33554431
        idmap gid = 16777216-33554431
        template shell = /bin/false
        username map = /etc/samba/smbusers
        winbind use default domain = no
[share1]
        writeable = yes
        readonly = no
        browseable = yes
        path = /smb/share1
        create mask = 0775
        directory mask = 0770
[share2]
        path = /smb/share2
        copy = share1
        guest ok = yes

Has anyone else experienced (and subsequently fixed) this problem with
XP Pro x64 and Samba?  I have searched Google and found a few reports of
Windows Explorer freezing but from the description it sounds as if the
PC can be recovered by killing the Explorer process in the task manager.
With my problem the PC is either completely locked or displaying BSOD.

Thanks,

Kevin