Upgrade error "Safe mode restriction"

I’m trying to upgrade to 3.01, can someone tell me what this error means?

Warning: touch() [function.touch]: SAFE MODE Restriction in effect. The script whose uid is 11373 is not allowed to access /tmp owned by uid 0 in /virtual/users/#####-####/web/wordpress/wp-admin/includes/file.php  on line 184

Download failed.: Could not create Temporary file

Installation Failed