[fel64]

There is a line in the quote plugin that converts all special characters to their HTML equivalents.

if ($row) echo htmlentities('<blockquote>'.$row->post_text.'</blockquote>');

(Some code is cut off to the side because of the forum’s limited width) I assume that the problem lies here. My guess is that it returns a different character format to the one your browser is using?

Get your quote.php file in your plugin folder and change this code to

if ($row) echo htmlentities('<blockquote>'.$row->post_text.'</blockquote>', ENT_COMPAT, 'UTF-8');

Upload the new version to your server and see if it works. If not, undo changes, save and upload the original file.

That’s just my guess; the first thing I would try. I don’t actually know.