Problems with blocks

I tried to create a new block for a yahoo goups promote link by inserting the tags. But after saving the block, the following message appeared:

user error: Duplicate entry '' for key 3
query: INSERT INTO boxes (title, body, info, format) VALUES ('', '\r\n\r\n
Click to join actphils_updates\r\n', '', 2) in /home/actphils/public_html/act/includes/database.mysql.inc on line 66.

warning: Cannot modify header information - headers already sent by (output started at /home/actphils/public_html/act/includes/common.inc:384) in /home/actphils/public_html/act/includes/common.inc on line 192.

This also appeared when i tried to create another block with an image. But when i return to the block list, it said that a new block was added but it does not appear on the block list.

I would really like to put images on my sidebar. How do i do it?

I'm using democratica theme and php format in my posts.