I get the following error only when trying to send off any kind of mail (New, Forwarded, Replied, etc)

CGI Error
The specified CGI application misbehaved by not returning a complete set of HTTP headers.

Windows 2003 Server
Sugar 4.2.1b
IIS 6
PHP 5.1.4
MySQL 5.0

I don't wish to downgrade PHP, though I've heard this will solve the problem. I'm only getting this error in this one spot, and would like to get any tips/tricks to fix whatever it's doing.

It's happening after the ENDING of the include of Save.php

However, I recieve the same error if I try die() at the end of Save.php to keep it from going any further.

Thanks in advance