problem with apache 2.0.43 and php4.2.3 not executing from default server.

It's an interesting problem. I have the default apache with a slew of virtual hosts and php executes everywhere correctly but from the default fully qualified server name. It's an internal site so you won't be able to try this out for yourselves but here goes. the address http://emerald.dex.uswest.com/test.php does not work. I get a premature end of script headers in the error log. The address http://emerald/test.php works just fine and gives the standard php test page. Any ideas on what is happening here? Thanks Allen abyingt@qwest.com