User not given permission to use folder

I manage a small system. We use SBS 4.5 running on an NT Server 4.0 (SP6) with Windows 2000 as the client.

I added a new user through SBS interface and gave him persmission to see two folders, Company and his personal folder on the server. When I log onto his machine, I can get access to his personal folder, but not the Company folder. I have even gone as far as given this user full rights to the folder, through the permission in settings on the company folder. Still no go.

All items that I have read point me to the LanmanServer Setting in my registry on the Server. It says that to fix this, reinstall NT.
I do not want to have to reinstall NT. Has anyone run into this problem before? Is there another fix? What are the correct settings for the LanManServer in the registry?

Thanks

Rob