Hi Franc,

One cause could be the fact that the cookie somehow does not make it to your browser for the domain you're loggin in to. The DOTNETNUKE cookie should be there. You could use Fiddler to check. Maybe your browser security setting does not permit it while it does allow it for the other domains.

If this is not the problem is sounds like something got screwed up during installation (maybe a timeout issue, not sure). In any case I can't offer an explanation but maybe a way forward. If the portal is real important to you then you could 'break in' given that you have host access. Presuming you get logged out when going to the portal, you could install a user switching module (there is a free one on codeplex I believe) that you could install on the installation and then manually put that one the home page of the faulty portal. Takes a bit of SQL reading and writing, but you should be able to make something like that show up. Then it should do the login for you. Alternatively, if the portal is not important (i.e. no content yet) I'd delete and try again.

My 2cts,

Peter