1.8.0.1 Fatal error?

Hi guys,

I have just installed the new version 1.8.0.1 using Softaculous in CPanel. When startimg my page I get this error message:  Fatal error: Call to undefined function mb_convert_encoding() in /home/s4lcom/public_html/mod/search/views/default/search/search_box.php on line 23

Does anybody know what this means?

Many thanks for your help!

Cheers, Chris