Sharepoint

I have an SSL vpn setup and working fine to access web based systems. In fact, I can access any web site on our network except for our sharepoint. The first time I try to access the share point site, it asks me for a user and password, but noting I put in there will work. After two failed attempts it doesn' t prompt me, and all I get is " The page cannot be displayed" . I have Ad working on this system, but do not think it' ll work that way for SSL. I have dug through the KB, but cannot find a thing. Thanks, dt