Cannot add pages

[amateur]

Hi,
Never seen this before;
I made a page (A4) and filled it with two images from a scanner. Then added speech bubbles and some lines. When I wanted to add a page, the menu item is grayed out, and adding a page is impossible. Also, the Object Gallery New fails to add a page (just a beep is heard).

Cannot disclose the actual page content. But, I have taken two screenshots, in case someone can find what the problem is.

Have already saved .xar file and re-opened; same result.

Using XXPro5(CD).

Regards
amateur.