[xwiki-users] XE 2.3 - cannot create new space

Dear forum, I am new to xwiki. Today I setup a xwiki (2.3) and have a try. When I tried to create a new space with the "Create" button on the Dashboard, I got an error page "Notice This document already exists." The same result using the create button on "New Page" panel. However, I was able to create a space with the Xwiki menu (I was using the default sking) and typing the space name in URL address (XXX/bin/view/NewPage/). Tried XE 2.2.6, there was no such problem. I checked the xwiki.log under Tomcat folder, there was no error message. (Is this right log to check error?) Any idea on this? My setup: Windows 2008 (Simplified Chinese, 32bit) MySQL 5.1.45 Tomcat 6.0.26 Thanks. Rex