Installation problem

[Zeratul]

I'm trying to install RoundCube 0.2.1...
I have PHP 5.2.9. and IIS 6.0.
I have this error on first step of installation (on START INSTALLATION button press):

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

But where is not such error on another site on this server.

How can i solve this problem?