I have gone through all messages in this tread,
Tried all the suggestions,

here is a video http://www.youtube.com/watch?v=fzlxI1...
it shows how the one portal 0 has a problem while the other 3 does not.

This means this is not web.config or portal files, but something in database or some portal specific setting somewhere.

Thank you for reply Sebastian,

Both portals use same skin,

I did try deleting all cookies for both portals, several times.
I use a chrome cookie addon "Edit this cookie" for chrome that you can view in the video, this gives me a very clear picture off all cookies on a website.

Portal aliases setting for the portals can be seen here on this image https://goo.gl/photos/4xYDcovZLJQyxAgf8

I've just got the same issue and I could identify the issue by running this query:

select l.listname,l.value,l.text,l.entryid, ppd.*
from ProfilePropertyDefinition ppd
left join lists l on l.entryid = ppd.datatype
where ppd.portalid=0
ORDER BY datatype

There was in fact a property referencing an "Unknown" type. I changed that to use the "TextEditorControl" instead, cleared cache, and it's fixed

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Vicenç Masanas
Banyoles, Girona - Spain