If you are using rpmforge with Centos 6.x you might run into this issue I found 2 packages with this issue mbcrypt and php-tidy. Both had the wrong setting in their .ini files. Just edit the files and replace “module” with the right module name.
Change
extension=module.so
to
extension=mbcrypt.so
and
extension=tidy.so
The .ini files are located under /etc/php.d/