Login in problem

[lcp03o]

Since upgrading my forum to version 3.6.7 Myself and users are having problems login in. I have seen the following problems

-I log in, it says re-directing you, but it hasnt loged me in, I still see the username + password boxes. But if I click on another page like one of my forums I can see I am logged in.

-People are also complaining they are getting logged out every time they go to a new page??

What I have done to my forum is the following. I have 1 board on version 3.5 and I had to do an import to a new board 3.6.7 using the impex tool.

Any ideas anyone ?? Thanks

I got it now, After looking at the config.php there was half missing ??? Must of been a problem uploading the file.