Thanks to all who have replied so far.

This app is a search engine with complex displays, and comprises 25 large perl files and hundreds of subs, so showing the relevant code is not possible. However, that gives me the idea of constructing a minimal program that exhibits the problem -- a well-known debugging trick that I forgot momentarily!

I was hoping someone had seen this problem before, or could diagnose it from the server output and what I said about the header. I've never seen it in 8 yrs of CGI programming in C++. It's the Perl and CGI.pm that are new to me.

I suspect it's something about the header I am sending, since the HTML output the server is sending is correct. Can anyone tell me if the default CGI.pm header as described in the original question is sufficient?

Thanks! Stephen Toney