vmwareuser and Sonic Wall

On a PC within a domain appears on the following problem.
The Sonicwall authenticates the user does not, although he correctly in the domain is registered. On the PC user does a VMware, but it is not a virtual machine is started, only the relevant processes that would allow it.The user must manually in the firewall log in to access to the intranet to get. If I get the IP address of the computer problem in the firewall search, I get a user "__vmware_user__."
Here are some questions. What the firewall detects the VMWareuser? It gets the info from the domain controller or from the PC itself? And if it is perhaps less a list of registered users on the PC there (undeclared domain users, vmwareuser) perhaps only the top users queried?
Well, perhaps someone has no idea, or something similar ever had.

The firewall when asked whether domain controllers after the domain user exists and what rights he has. The work reports to the domain controller. The firewall will now ask you again directly with the client and noticed the VMware ?Or where to get this info?

Please, no such general questions.

Because the answer to such questions (which uses someone ...) can only be yes.

It is missing in your description of these particulars:

What Sonic Wall model? There is not only a model of Sonic Wall.
Which Windows domain? There are Windows 2000, 2003 and 2008.

Likewise, even when Windows client: Which operating system? 2000, XP Professional or Vista (Business, Ultimate)?

The authentication can a) radius over - for Windows 2000 Internet Authentication Services called - or b) about LDAP requests come.

What exactly is in use, hangs a) used by the domain, b) of Sonicwall model and c) by your configuration.