cad block exploding when multiple copied

hi guys,
i have created a cad block of an 8 feet high brick pier sitting on a 450mm er...whats that in inches?...um...say 18" concrete round pad. anyway the exact dimensions are inrrelevant for my question...moving along...

when i go to the library grab the cad block and place it in my drawing i get exactly what i expect. a concrete pad with an 8 feet high brick pier sitting on top.

however, when i multiple copy the original block in one direction, then attempt to multiple copy the same one in the perpendicular direction i lose either the pad or the pier!

in order to complete the second series of multiple copies (of the block originally inserted into the drawing remember) i have to unselect and reselect by dragging a box over both objects in the block in order to copy them.

why is that happening? it seems to be exploding the original cad block when i multiple copy, without me having chosen that option!

dont worry, its stopped doing it now.
it must have just been a little quirk or something, cause i have come back to the drawing after doing something else for a while and it isnt doing it now.