The specified CGI application misbehaved by not returning a complete set of HTTP headers.
This seams to be an ongoing problem with IIS (Microsoft's end). Never heard of such a issue with CB which leads me to believe is hosting environment related. Please see the below PHP bug ticket (very old), which has various fix proposals (dating to 2010).
bugs.php.net/bug.php?id=25863
Please also see the following MS articles concerning the issue.
support.microsoft.com/default.aspx?scid=kb;EN-US;884764
support.microsoft.com/kb/145661
Easiest approach is to simply upgrade to IIS 7 where the issue appears resolved.