I'm experiencing some issues with the Posts By Tag plugin when using content="true". It's been working great for months, then suddenly - I think it was either with the last plugin update, or the WordPress 3.5 update, it suddenly started making the page load completely blank.
You can see it here: http://denverbargains.com/denver-milk-prices/
Here is a sample of what's on that page:
[posts-by-tag tags="milk prices" number="15" thumbnail="false" order_by ="date" content="true"]
When I remove content="true", the page loads fine. It started happening when I updated the plugin in the last week or two; unfortunately, I'm not sure if it's a plugin or WordPress issue since I updated both around the same time. I'm using the same plugin on a different site with the same issue.