Single Sign on to Domain not working

I have an OS X 10.5.6 client and it is successfully had been bound to the domain. The account shows up and I can log in using any domain user and password. However; when I try to "mount" or browse a share (I press the apple key + k) and I type in SMB://server/fileshare it prompts me for a user name and password. I can type in my user name and password and successfully access the shared resource. I want to just be able to browse / mount shares with out having to enter the user name and password, Am I missing somthing here? Itsn't that the point of single sign on? I have NOT extended my schema, is that why? Just verified as well using Kerberos.app that I have a valid ticket that will expire in 9:58. Still being prompted for a user/pass when trying to connect to a share. I used a utility to disable the Bonjour Service I have set DSCINFIGAD -namespace forest I have added my domain to authentication search accounts I have added my domain to search policy / contacts This is what I have done, what am I missing? This is a laptop, I have tried with different user accounts, and I have tried using a mobile account and a non-mobile account. Please help. And Thanks