Users on my site cannot submit comments when using IE6 unless they have signed in. This means that guests cannot submit comments using IE6.

I have tested it on IE7 and other browsers. Users and guests not signed in can successfully submit comments using IE7, as well as Firefox, Safari, Opera and other browsers. So the problem seems confined to IE6.

Captcha is working fine on other browsers (and even IE7) for users who are not signed in and with guests (who are not registered) try to submit comments.

I have a default 3.26 installation, with nothing customized, and I'm running Joomla!1.5.6. I do intend to upgrade to 1.5.7 soon, but am trying to fix some other issues first.

Here are some pertinent settings:
[ul][li]Only registered = No[/li][li]Autopublish comments = Yes[/li][li]Captcha Enabled = Yes[/li][li]Captcha Usertypes: Unregistered[/li][li]Ajax support = Yes[/li][/ul]Any help will be appreciated.