I hit a strange problem today when I started getting the ASP.NET 404 error page whenever I tried to access my ASP.NET pages through IIS – whilst any non-ASP.NET pages in the same directory worked fine. After a bit of digging, it turned out that this was caused by me fiddling with the site’s “home directory” in IIS – I’d put it back to it’s original value, but with a trailing backslash… so

c:inetpubwwwroot <– this didn’t work

instead of

c:inetpubwwwroot  <– this worked

I removed the trailing backslash, and everything was fine again. Very wierd!