[horde] Login page redisplay's repeatedly

[Mike]

After a recent upgrade to my Ubuntu 12.04 server where php5 was  
updated to 5.3.10, login stopped working.

Poking around lead me to change in horde/config/conf.php:

$conf['session']['use_only_cookies'] = true;

to false.

This seems to have fixed the problem, but I thought I'd reach out to  
the list to see if someone might be able to offer a reason why?

Also, does this create a security issue?

I'm using Groupware 5.1.6 installed via pear, if that matters.

Thanks for any help or links you might provide.

Mike B.