When running a Security Essentials scan, I was surprised to find a Trojan detected in a file I downloaded from joomla51.com. (See pic).

Microsoft offered this info about the Trojan:

Trojan:JS/HideLink.A
Alert level: Severe First published: Jun 24, 2015
Latest published: Jun 25, 2015
This threat is a malicious JavaScript file that can open hidden content as you browse a website. It does this to improve the ranking of the targeted content in search engine results. We have seen this threat added to compromised websites running vulnerable versions of Joomla and WordPress.

This came from a download link in my Downloads section of Joomla51. Thought others might want to know.