500 internal server error

Hello, Since some time I had an error in CB. Whenever I want to send a verification email after creating a user, or when I want to send a new password from the frontend, I've got the error:

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@.......... and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

In the server errorlog I found the following error:
malformed header from script. Bad header=More than one "from" person: php, referer: http://.../index.php?option=com_comprofiler&task=lostpassword&Itemid=20

Can anyone help to find the reason of this error?

First post = welcome to the forums.

Google says :

Cause:

This error can be caused by a variety of issues but is most likely caused by a corrupt .htaccess file. Check to see if there is an .htaccess file in the directory where the error is being generated or any directory above in the tree. If so, temporarily rename the .htaccess file and refresh the page. If the error does not reappear, the .htaccess file is the issue. Repair the file or leave it disabled.

Most of the time .htaccess issues are caused by trying to overwrite PHP settings, being uploaded in binary format or permissions issues.

Resolution:
Be sure to upload .htaccess files in ASCII mode
Set the permissions to 644, which makes it usable by the server, but prevents it from being read from a browser.
If you are trying to make changes to PHP settings, be sure to make said changes to the php.ini or php5.ini file (depending on the version you are using).

Also:

• Version of CB?if it's not current, please upgrade
• Version of Joomla?if it's not current, please upgrade
• Check your SEO/SEF settings
• Disable (one-by-one) any 3rd party extensions

Best-