MYSQL dll problem

Hi,
I have a bit of a problem using Mysql with php. I have installed Mysql 5 and
PHP5 successfully, but I can't load the php_mysql.dll and php_mysqli.dll.
The PHP phpinfo(); function says it can't load the modules. The dll files
are in the c:\php\ext folder, and it's exactly where the test page says it
can't load it from. The extension_dir is set to "c:\php\ext" so, that's not
wrong. On an another computer everything works fine, and I don't think I
have done anything different.
Ideas anyone?

check the permissions of the file such that the owner of the web
browser can see them...