This problem has a solution:
http://commonsense360.com/?p=14
From the MistyLook support site:
“You are using WordPress 2.3.1 and MistyLook 3.2. They don’t cooperate together.
Please, download the newest version of ML (3.5) which works with new features WP 2.3.1 offers.”
This error message usually is caused by white space before the beginning <? or after the closing ?> php tags. Some editors add spaces to the end of the file that shows up as blank lines after the closing tag. You might want to check that in the files named in the error message.
hope this helps, mikesz