Can't add custom content or custom php content

Hi,

When I try to add custom content or custom php content, I get the popup and can enter the data, but when I click "add pane" I get sent to a url like:

http://[domain]/panels/ajax/add-pane-config/1/left/custom/custom

which has something like the following in the body:

{ "type": "add", "region": "#panel-pane-left", "id": "#panel-pane-new-5", "output": "\x3cdiv class=\"panel-pane\" id=\"panel-pane-new-5\"\x3e\x3cdiv class=\"grabber\"\x3e\x3cspan class=\"buttons\"\x3e\x3ca href=\"/panels/ajax/hide/1/new-5\" class=\"panels-ajax-link pane-toggle-shown-link panels-no-modal\" title=\"Hide \x26quot;Custom (test title)\x26quot;\" alt=\"Hide \x26quot;Custom (test title)\x26quot;\"\x3e\x3cimg src=\"/sites/all/modules/panels/images/icon-hidepane.png\" alt=\"\" title=\"\" width=\"16\" height=\"16\" /\x3e\x3c/a\x3e\x3ca href=\"/panels/ajax/configure/1/new-5\" class=\"panels-ajax-link pane-configure-link\" title=\"Configure settings for \x26quot;Custom (test title)\x26quot;\" alt=\"Configure settings for \x26quot;Custom (test title)\x26quot;\"\x3e\x3cimg src=\"/sites/all/modules/panels/images/icon-configure.png\" alt=\"\" title=\"\" width=\"16\" height=\"16\" /\x3e\x3c/a\x3e\x3ca href=\"/\" class=\"pane-delete\" id=\"pane-delete-panel-pane-new-5\" title=\"Delete pane \x26quot;Custom (test title)\x26quot;\" alt=\"Delete pane \x26quot;Custom (test title)\x26quot;\"\x3e\x3cimg src=\"/sites/all/modules/panels/images/icon-delete.png\" alt=\"\" title=\"\" width=\"16\" height=\"16\" /\x3e\x3c/a\x3e\x3c/span\x3e\x3cspan class=\"text\"\x3eCustom (test title)\x3c/span\x3e\x3c/div\x3e\x3cdiv class=\"panel-pane-collapsible\"\x3e\x3ch2 class=\"title\"\x3etest title\x3c/h2\x3e\x3cdiv class=\"content\"\x3e\x3cp\x3etest custom content\x3c/p\x3e\n\x3c/div\x3e\x3c/div\x3e\x3c/div\x3e" }

If I click the browser back button, I get back to the content tab but nothing has been added. I have tried with FF2 and IE6, with the same results. Other content types that I have tried seem to work fine.

I also noticed that the "input format" section is not a link, so I have no option to choose filtered or full html etc.

Using Drupal 6.9

Cheers,

Ben