Trouble shoot webserver phpbb issue - Very Urgent

Hi, we are in need of an expert to save our day!

We have migrated our website and phpbb forum to a new VPS running Linux CENTOS 6.

Unfortunately after our host transferred our data, phpbb forum and MySQL databases from their shared hosting solution to their VPS service our forum is broken and gives the error message:

Fatal error: Cannot redeclare class cache in /home/rikomagi/public_html/forum/includes/cache.php on line 24

The address of the forum is
http://www.rikomagic.co.uk/forum

We understand this could be a php configuration error but we need urgent help to solve this problem as quickly as possible.

Thanks,

Andy