I'm having an issue that's driving me mad. I've installed a WSS 3.0
site, and several of the URL encoded pages return 404 errors. For
example, I've enabled anonymous access on one of the sites, and the
Sign In link returns a 404. The link is
http://internet/_layouts/AccessDenied.aspx?
loginasanotheruser=true&Source=http%3A%2F%2Finternet%2Fdefault%2Easpx

However, http://internet/_layouts/AccessDenied.aspx?
loginasanotheruser=true&Source=http://internet/default.aspx works fine.
The same thing happens when I view the properties of a document in a
document library. The properties page returns a 404 unless I replace
all of the URL encoding with the real values.

I've already tried re-installing the entire WSS instance, and that
didn't work, so I suspect it might be a problem in IIS???