Attempted zip download blocks future requests to domain

I have experienced a strange problem. I have a zip file on my web site that
I sometimes download at client locations. Recently, attempts to download it
have timed out, and then any future attempts to view any page on my site, or
any page for other sites hosted at the same IP address, have gotten a "page
not found" error page (not only on the machine where I attempted the
download, but on other machines at the same location).

Is this likely to be due to a bit pattern that matches a virus signature?
And somehow the server is "blacklisting" that IP address?
Received on Mon May 1 00:50:24 2006