Forum Upgrade to 4.0.2 PL1....Small problem
 

I just upgraded my site from 3.8.4 PL2 to 4.0.2 PL1 (Forums only) the whole upgrade worked flawlessly right up to the final stage of rebuilding the search index.

When I try to do this, even from the Admin panel maintenance section I get the following error:-

Fatal error: Call to undefined function ctype_alpha() in /home/********/public_html/admincp/misc.php on line 146

Anyone have any ideas ???