If running apache on Windows it can be fixed by
adding index.php to the welcome file list in my apache httpd.conf file
#
# DirectoryIndex: sets the file that Apache will serve if a directory
# is requested.
#
<IfModule dir_module>
DirectoryIndex index.html index.php
</IfModule>
Yes, I was able to get to wp-admin/index.php but not the rest of the site.
I have fixed it now by adding index.php to the welcome file list in my apache httpd.conf file
#
# DirectoryIndex: sets the file that Apache will serve if a directory
# is requested.
#
<IfModule dir_module>
DirectoryIndex index.html index.php
</IfModule>
I get the same behaviour as you, except I do not get the error message. Instead I get the dir listing.
I have installed 3.0 on apache 2.2 on localhost on my windows laptop with php 5
