I registered two days ago and I am also suffering from the problem of being logged out or not being able to post replies etc. etc. unless I retry about three times or so each time.
I'm am by no means an expert on this forum software but I have noticed this behaviour with many other forums that I belong to and have also managed to find the workaround.
Take a look at this one's login page for instance (and all of the others that I belong to are setup exactly the same):
http://www.dvinfo.net/conf/
You will see in the top right hand corner that aside from the 'Your Name' and 'Password' inputs there is also an option to 'Remember Me'.
With this particular forum I know that if I do not put a tick in the 'Remember Me' block and just login I get exactly the same behaviour as I do on this forum.
I noticed that this forum does not display the 'Remember Me' option and I am assuming that it is an option in the software setup or something like.
What I do know is that by selecting the 'Remember Me' option a cookie is created on your local workstation and stays there until you logout.
Maybe not the fix but place for your IT person to start (if that person has not done so already).
Just trying to help.
Regards,
Dale.