CMS Pages

Hi
I’m new at this peace of art .
I was wandering if you could please help me in solving the following problem which is doing my head in
I’ve just installed monstra v 2.3.1  on hosted site

•    PHP version   - 5.2.14
•    PHP Built On  - Windows NT WEBS3064 6.1 build 7601
•    WebServer to PHP Interface - Microsoft-IIS/7.5
•    SimpleXML module – Installed
•    DOM module – Installed
•     Apache Mod Rewrite - Installed

I’m using the default template and for some reason if create a new page (and on any new page)  , the server display the following message “HTTP Error 404.0 - Not Found The resource you are looking for has been removed, had its name changed, or is temporarily unavailable
page the server 

Any Idea? thanks in advance
Akylle