Hi Joe,
When a user is on a blog post page and they enter a search term into the SearchInput and either press enter or click the search button, they are returned to the current page. The issue only appears when the site is using Extension-less URLs. I even tried using the non-friendly URL but I got the same result. There aren't any errors written to the log when this occurs.
A skinning customer of mine found this on his site (not my hosting) and then found that my site does the same thing. You can see the problem in action at http://i7media.net/mojoportal-logs-hidden-in-plain-sight.
I have seen this problem in both 2.3.5.5 and 2.3.5.8. I am not sure if it existed before that because I don't have an older installation to test against. Also, the problem occurs in both .NET 3.5 and .NET 4.0. I mention this because of the new way that .NET 4 handles extension-less URLs.
If you need more information, please let me know.
Thanks,
Joe D.