Came across troubleshooting an issue with a site collection with the name bin. This site collection had a url like http://portal/sites/bin, making the default homepage http://portal/sites/bin/default.aspx. For some reason the site did not render and I got a HTTP 404 error. After analysis of the ULS logs not showing any trace of the request and the analysis of the IIS logs, I wnet looking for an answer on the interwebz. Stumbled upon the following article from Russ Michaels : http://www.michaels.me.uk/post.cfm/iis7-blocks-viewing-access-to-certain-folder-names
As it appears IIS 7 blocks access to urls where /bin/ is present in the Url.
The solution to this problem is to rename the site collection or remove the exception in the web.config of your web application as suggested by Russ.
I prefer the web.config approach on the web application level by adding the following section:
<?xml version="1.0"?> <configuration> <system.webServer> <security> <requestFiltering> <hiddenSegments> <remove segment="bin" /> </hiddenSegments> </requestFiltering> </security> </system.webServer> </configuration>