Hey there!
I have P9 running on my Site and some of the users experience trouble logging into the forums. When those users try to login via the forms (login upper right or forms under the boards) they get back to the login screen for no reason. What they can do is to use the link provided in their activation Email. They only get an error message that they´re already activated but after that they can use the boards.

I told them to refresh the page on the login-screen and to empty their browsers cache but nothing worked. It´s a standard P9 installation with some extra usergroups and without the Moderators group (I decided to delete this one and to redefine some other groups). It´s a problem that only a few members have. I´m not shure if it can be a forum-bug or if they´re doing somewhat wrong with their browsers (no exotic ones, they use firefox/msie).

Thanks for any ideas!

When you say some? do you mean one or two people? If all of your other users can view/log in etc, then it will be a browser problem.
Check and see what *other* things they have running in the background?

I agree with Nat,

When they have this problem, get them to delete their cookie cache and temp files and see if it makes a difference to them.

Aah, the cookies - didn´t let them try these ones out. I´ll let them check their cookies and options of their browsers. There are only 5-6 of all users having trouble.

OK then, "I´ll be back" with more info

I´ve enabled the Session IDs and now those users can login.

They enabled cookies for my site but still couldn´t log in before. When they entered their name/pw the forum still showed them as guests.

I don´t knwo what´s going wrong, it´s not their cookies-settings, nor their cache.

The quickest way to resolve what may be the problem is to have them log into your forum from a different PC.. even if it's the public one at the library.

It certainly sounds like Browser / Windows Internet 'options' problems. But you would have to now disable cookie sessions to come to the source of the problem.

This sounds like the problem I was having with my message board.  Warlock and I worked on it for quite a bit of time before figuring it was likely a conflict of some sort with my host (Netfirms).

I had done a host switch and an upgrade from eBlah P5 to P9 at the same time.  I still had access to my previous host, so Warlock did the upgrades on that host (from P5 to P9) and the users that couldn't login were then able to login.

Seemed really fishy, and I can't be 100% that it was the host causing the problem, but I desperately wanted the problem resolved as I didn't want users not being able to login, so I switched back to my old (and more reliable) host.  Now all my users can login.