[Samba] Problem with offline drive

[BOURIAUD]

Hi !
I hope that someone will be abble to help me with the problem I get with my 
samba machines, though it is not really a samba problem.
Here is the config I use :
I'm running a samba controler on a rhel 5 machine (rpm -qa says 
samba-3.0.33-3.7.el5) which acts as a domain controler.
My machines, all windows XP use to be connected to this controler. I have no 
problem with them. The problem occurs with laptops.
Indeed, we have some drives mapped to the domain controler. The one that 
causes problem is the M: drive, on which is stored the profile of thunderbird.
When the laptop is connected to the network, no problems. Thunderbird works 
just fine. All mails are here. 
When the laptop is out of the office, connected or not to another network 
doesn't change anything, thunderbird shows a weird interface, there are 
missing mails, missing folders on the left view and so on.
When I connected the M: drive to \\server\mail, I right-clicked on the M: 
drive in the "My computer" view and selected the option to have this drive 
offline. When I'm disconnected of the network, I can walk in this drive and 
see all the files that belongs to thunderbird. I even can view the content of 
individual files with notepad for example.
Is there anyone here either to help me or to direct me to another place where 
I could find help for this peculiar topic ?
I've of course searched the web, read many things about offline drives, but 
found nothing helpfull.
Thanks in advance for any help provided.