I am having that error and here are the contents of the log file:
Zenphoto Setup v1.3[5479] Tue, 15 Jun 2010 15:54:55 -0500
Full environment
pass: PHP version 5.2.12
pass: PHP `Safe Mode`
pass: PHP `magic_quotes_gpc`
pass: Graphics support: `PHP GD library [i]bundled (2.0.34 compatible)[/i]`
pass: PHP `gettext()` support
pass: PHP `mbstring` package
pass: PHP `MySQL support`
pass: [i]zp-config.php[/i] file
pass: File/Folder Permissions [are [i]strict[/i] (`0755`)] <p>If file and folder permissions are not set to [i]strict[/i] or tighter there could be a security risk. However, on some servers Zenphoto does not function correctly with tight file/folder permissions. If Zenphoto has permission errors, run setup again and select a more relaxed permission.</p><p>You must be logged in to change permissions.</p>
pass: MySQL setup in [i]zp-config.php[/i]
pass: MySQL version 5.0.89
pass: Connect to the database
pass: MySQL `SQL mode`
pass: MySQL `access rights`
pass: MySQL [i]show tables[/i] found: `administrators`, `admintoalbum`, `albums`, `captcha`, `comments`, `images`, `obj_to_tag`, `options`, `tags`
warn: MySQL `$conf["UTF-8"]` [is not set [i]true[/i]] You should consider porting your data to UTF-8 and changing the collation of the database fields to `utf8_unicode_ci` and setting this [i]true[/i]. Zenphoto works best with pure UTF-8 encodings.
pass: Zenphoto core files
pass: [i].htaccess[/i] file ([i]RewriteEngine[/i] is [b]ON[/b])
pass: [i].htaccess[/i] RewriteBase is `/zenphoto`
pass: [i]robots.txt[/i] file [Not created] <p>Setup did not create a [i]robots.txt[/i] file because one already exists.</p>
pass: [i]albums[/i] folder
pass: [i]cache[/i] folder
pass: [i]locale[/i] folders
pass: [i]uploaded[/i] folder
pass: [i]zp-data[/i] folder
pass: [i]HTML cache[/i] folder ([i]cache_html[/i])
pass: [i]Third party plugins[/i] folder ([i]plugins[/i])