Thanks for getting involved in this issue. What details would you like of the hosting environment? My PHP version is 5.2.16, SQL is 5.0.92 and WP version is 3.2.1.
What I had to do in order to add a new page as a child of the WP Client page is to first of all remove the Private permissions on the WP Client page (otherwise you are unable to add a child page to a Private page) Then create a new page with the WP Client page as the Parent page and then make them both Private!
From there I am then able to upload files to that page but they only show up a “Download” link so you’ve no idea what you’re downloading and you can’t click to “View Page” in the WP Client Share Admin panel.
There really are too many issues at the moment to go through them all. I’m more than happy to add you as an administrator of my Dev site. Please let me know. I’m not sure if you can send me a Private Message or anything similar?