[Samba] samba share problem accessing from w2k client

[J. van Santen]

Hi,

I got a problem with accessing some share's on my samba PDC (3.0.14)
When a user tyr to access a share for which he is not authorised a box
show up to suplly a name and password to access the share.
Why doesnt the user get a box with 'access denied'?
When u supply a username (DOMAINNAME\USERNAME) and password which is
authorised for the share u get the message: 'SERVERNAME\SHARENAME access
denied. the credential supplied conflict with a existing set  of
credentials'

What could be the problem?
Im using samba 3.0.14 with tdbsam as backend. security is set to user.
an example of a share defined in smb.conf:
[example]
	comment = example
	path = /example
	invalid users = user1
	read only = No

I hope someone can give me the answer

Joshua