When i try to edit or create a new category in K2 latest version i get the follow error message
"500 - An error has occurred.
Unable to load format class

Return to Control Panel

Call stack
# Function Location
1 JAdministrator->dispatch() /home/stati416/public_html/administrator/index.php:47
2 JError::raiseError() /home/stati416/public_html/administrator/includes/application.php:164
3 JError::raise() /home/stati416/public_html/libraries/joomla/error/error.php:215

System Information
PHP Built On Linux hp87.hostpapa.com 2.6.32-131.17.1.el6.x86_64 #1 SMP Thu Oct 6 19:24:09 BST 2011 x86_64
Database Version 5.1.56-log
Database Collation latin1_swedish_ci
PHP Version 5.3.8
Web Server Apache
WebServer to PHP Interface cgi-fcgi
Joomla! Version Joomla! 1.7.0 Stable [ Ember ] 19-Jul-2011 14:00 GMT
Joomla! Platform Version Joomla Platform 11.1 Stable+Modified [ Ember ] 01-Jun-2011 06:00 GMT
User Agent Mozilla/5.0 (Windows NT 5.1) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/15.0.874.121 Safari/535.2

PHP Settings
Setting Value

Safe Mode Off
Open basedir None
Display Errors On
Short Open Tags On
File Uploads On
Magic Quotes On
Register Globals Off
Output Buffering Off
Session Save Path /tmp
Session Auto Start 0
XML Enabled Yes
Zlib Enabled Yes
Disabled Functions dl,passthru,proc_open,proc_close,system,allow_url_fopen
Mbstring Enabled Yes
Iconv Available Yes

Does anybody know how i can rectify this problem

Thankyou