i had a same problem!
I found solution from here: http://forum.joomla.org/viewtopic.php?t=808997
and here: https://github.com/joomla/joomla-cms/pull/1309/files
Open:
libraries/joomla/filter/input.php
And change Replace two lines..
Find
// Convert decimal
$source = preg_replace('/&#(d+);/me', "utf8_encode(chr(\1))", $source); // decimal notation
Replace with
$source = preg_replace_callback('/&#(d+);/m', function($m){return utf8_encode(chr($m[1]));}, $source); // decimal notation
2nd line, Find
// Convert hex
$source = preg_replace('/&#x(+);/mei', "utf8_encode(chr(0x\1))", $source); // hex notation
Replace with
$source = preg_replace_callback('/&#x(+);/mi', function($m){return utf8_encode(chr('0x'.$m[1]));}, $source); // hex notation