URIs in your registry can launch applications according to this article. Some vendors make registry entries with these URIs to make it easier for people to launch applications, however this can lead to serious security flaws:
http://www.networkworld.com/news/2007/081507-new-uri-browser-flaws-worse.html?t51hb&nladname=securityal
Check your registry. Maybe we need Microsoft to wire a tool that reports all these URIs so you can remove them if you don't need or want them on your system.