Update (2014.11.24): The post below references an issue with a Component in CQ 5.5. I finally heard back from Adobe support and the issue has been resolved in CQ 5.6.1 by removing the Adaptive feature. They provided this forum post as a reference. Recently I was perusing crawl errors from Google’s Webmaster Tools to find any issues that had not yet been reported. I came across dozens of 500 errors coming from requests to one particular page.