I discussed URL sensitivity issue back in March 2005 (http://blogs.msdn.com/junfeng/archive/2005/03/20/399418.aspx). In that post, I mentioned fusion probes assemblies with the extension capitalized (For example, http://foo/bar.DLL, instead of http://foo/bar.dll.)
Turns out in .Net framework 2.0, we have a regression on http based LoadFrom, only repros if the web server is case sensitive.
This bug is first opened in MSDN feedback center on May 07, 2005. (http://lab.msdn.microsoft.com/ProductFeedback/viewFeedback.aspx?feedbackid=c5f277ef-8c9d-4bc0-b86a-f02d2ced5c92). Unfortunately it is only made to my attention after .Net framework 2.0 has shipped. It is fixed in the latest source tree since. To get the fix for .Net framework 2.0, you have to contact Microsoft Product Support. This is unfortunate. But it is the best we can do at this timeframe.
To workaround the bug, make sure the URL has the file extension capitalized.
It is not appropriate to discuss the technical detail on how we regressed. But suffice to say that it is related to moving the LoadFrom’s second bind to fusion.
It takes a while for us to repro this problem, as we literally have to setup a Unix box and Apache server, and configure the box properly. This is what happen when you are running Windows 100% 24/7.