My b2evolution Version: Not Entered

Hello all,

I'm new with b2evolution , and I download the last version (2.4.1), and I had one error when I try to send comment or preview the comment (Error HTTP 400), the page don't back to the original post.

My system are:
b2evolution: 2.4.1
web server: Windows 2003 server with IIS 6.0
MySQL version5.1.23-rc-community
PHP version5.1.2

I try to folow something in other topics, but not worked....

Any idea???

Thanks for all.