Can't insert text cursor; text is selected as image?

Hi all. Occasionally, as I type in Structured FrameMaker, this happens.

When I try to insert a text cursor the entire page is selected with black dots in the page corners and the middle of each margin. Basically the page is selcted as if it were an image and I can not insert a cursor; all it does is select the page as one entity (with the black dots). I don't even know what this is and the only way I seem to be able to fix it is to close Frame and restart Windows (just closing doesn't work). Can someone tell me what this is and how I can rectify this situation without closing FrameMaker?

A hint: I think this happens if I accidentally click one of the modifier keys (CTL, Command, etc.) but nothing I do after changes it back. I am using Frame in Virtual Box Windows on a Mac.

thanks

michael