aristotle - 10:02 pm on May 14, 2010 (gmt 0) [edited by: tedster at 12:24 am (utc) on May 15, 2010]
I might have discovered why the Google Search Preview option shows blank rectangles instead of screen shots for one of my sites.
In looking at the site's error logs, I saw that my hotlink protection has been blocking webcache.googleusercontent.com.
I don't know for sure if this is causing the problem, but I have just changed .htaccess to allow access for this, and will see what happens.
[edit reason] clarify the blocked domain [/edit]
[edited by: tedster at 12:24 am (utc) on May 15, 2010]