Logged In: NO

The solution is:
trasform only the new resolution in html format.

I use a new resolution1 variable that contain only the new
resolution input text.
Then I parse only this variable with htmlentities and after this I
add this string to the oldest resolutions into the $resolution
variable.

if ($HTTP_POST_VARS["newresolution"]){
$resolution1 = "$now - $login wrote:
\n" .$HTTP_POST_VARS["newresolution"]."\n";
}
#look for any special characters
$title = htmlentities($HTTP_POST_VARS["title"],
ENT_QUOTES);
$description = htmlentities($HTTP_POST_VARS
["description"], ENT_QUOTES);
$resolution1 = htmlentities($resolution1, ENT_QUOTES);
$resolution .= $resolution1;

it should then work well