Vista Tutorial - Vista Ultimate unable to join domain

HELP!!!
just purchased 2 laptops with vista home premuim, upgraded to ultimate
because these are used in an office enviroment, in a windows 2003 AD, both
were able to join the domain without any problems, suddenly one was unable
to see network shares, removed from domain (to workgroup) and now it does not
want to join the domain, nor I can see any network shares. it gives me :

"The format of the specified network name is invalid" error.

I have:

changed the name of the computer (ILSPC01)
verified the DNS is the same as the AD
can ping to the server name
able to browse internet
re-installed vista ultimate
removed hard drive and installed on other latptop (same symptoms)
removed entry from active directory
reset computer in AD
conected wireless, conected directly
manual IP, DHCP IP
disabled firewall
disabled tcp v6
netdiag and dcdiag without any errors
installed an external nic
able to ping by name and nslookup
only have one DNS, and its the DC
update latest hotfixes
ran vistas diagnose without any errors
no errors en event log
tried FQDN, server. local, server.domain.net, domain.net, etc etc etc

Im out of ideas.. please help!
this is teh bosses pc, to make matters worse...

damm vista!

sysprep wrote:
try here:
http://www.chicagotech.net/vista/vista&domain.htm