every time i post a comment to a photo, a fatal error occours:

Fatal error: Call to undefined function fetchComments() in www.mysite.com/htdocs/gallery/zp-core/functions.php on line 971

but the comment will be saved.
how can i do to fix it?

and i got another problem, when i try to use the find finction i got another fatal error:

Feed for this album: Fatal error: Call to a member function getFolder() on a non-object in www.mysite.com/htdocs/galleria/zp-core/template-functions.php on line 3709

Your fatal issue:

Fatal error: Call to undefined function fetchComments() in www.mysite.com/htdocs/gallery/zp-core/functions.php on line 971

at least on my server had to do with the Admin|Options|Comments configuration. In order for the error to go away is to uncheck 'Enable comment notification:' Once this is unchecked the error goes away. Now I didnt see anywhere to add SMTP information, so I would just uncheck it.

As for your second error I have yet to see it.

Problem #1 is fixed in the nightly builds. #2 is an error in the stopdesign search script. It is trying to place an RSS link for an album feed. That will be corrected in tonight's build.

If you just want to fix the problem then delete or comment out the line 971 in functions.php:

$last_comment = fetchComments(1);