Cannot access mapped drives while using netscreen remote

giltjr is correct

Make sure that when the user connects through the VPN that it is handed an IP address on the main network AND is configured with the Domain Controllers as the DNS servers.

If that doesn't fix it, try specifying the fqdn, meaning "computer.domain.tld" instead of just "computername:

i.e., "net use h: \\server.domain.com\share" instead of just
"net use h: \\server\share"

If that fixes your problem then it's because the remote computer is not a domain computer and has a different suffix.  You have to configure it to use "domain.com" as the default suffix when connecting to that network.  In the Microsoft Windows VPN Client, this is located in the settings for the VPN Connection, but with netscreen, I'm not sure how you can do it.

"The local device is already is use" DOES mean that the drivers are already mapped to something.  It is good practice to delete the existing mappings first.

So before "net use h: \\server\share"
you should put "net use h: /d"

when prompted for a username and password, try specifying the domain name, along with the username like this "NTLMDOMAIN\username"  Note the NTLMDOMAIN is the Pre-2000 version of the domain name, not the FQDN (which contains dots... 'domain.com')
 

There are issues that are known with NSR 8.6 too:

http://www.juniper.net/techpubs/hardware/netscreen-remote/v8.6/NS_Remote_RN8.6_C.pdf

NetBIOS Protection now user-selectable  The NetBIOS Protection
options in the Personal Firewall are now user-selectable. The user may
disable NetBIOS Protection if desired or if they encounter problems
mapping network drives over a VPN.

Delete the users acounts and re-create a new set
 if the previous are still regestered if the ethernet cables were still connected the regestry may not have updated.
>>running a 2003 Active Directory domain which I recently upgraded from NT4
something like that its best to delete old accounts after upgrading.

Aplogies for not getting back sooner I have been ill for the past couple of weeks.

adamdrayer: I spoke with the company who manage our VPN connection and they said that the firewall box is unable to designate an internal IP address and also DNS addresses, does this sound true to you?

I have installed a draytek vigor 2800v I have set this up to give remote users an internal IP address but I am unsure how to set dns addresses from the router, is this even possible?

Is ther a way of possibly connecting to the network BEFORE logging onto windows? And if this is possiblewould this inturn then run the log on script when the user does log in to windows?

Can you post the configuration of the netscreen device?

As well, you could choose for authentication via radius tied to Active Directory.

Cheers,
Rajesh

Unfortunately because the netscreen box is managed by an external company who are probably more than aware that I am trying to use a different option then themselves, and the box is actually their property I cannot get access to the box.

Would I use the Netscreen box to connect via RADIUS or could the Draytek router do this?

You can configure radius on the netscreen and have users authenticated. One typical way would be to use Windows IAS as radius server and have users authenticate to Active Directory.

Cheers,
Rajesh