catalogue has disappeared on screen!

Hi, I'm very new at all this and my catalogue has disappeared on screen - 
well down to a little green bordered rectangle but is still there when I 
click on configure. But when I try to adjust the size of the catalogue 
bounding box (is what where I should be adjusting) in the catalogue 
properties box, the whole program crashes, so I am getting nowhere fast! I 
think it is something to do with the layout properties. I can't seem to get 
the layout border at the right to move over. If I click on zero margins, 
everything disappears. I'm just going to look at the help files again! Any 
help really appreciated as I can't move on.

Lorraine