I have got the very same problem on a fresh new install (first one for me). I have done everything!
-the memory in the php.ini file was set at 128M so I changed it to 64M. -Did the same thing in wp-config.php
-phpinfo.php looks OK, has a mysql field
-I echoed something in the install.php and it shows it
-I set in .htaccess a line with
php_value display_errors '1'
and no errors. Just a blank page dislaying the echo sentence
Win Vista with last version of Easyphp and WordPress running on my laptop
I read on a forum something about permissions. Could it be? The user in phpmyadmin has global privileges