View property disappears after editing object

hi,

I am working on some 3d autocad (2008) model, and sometimes it is going painfully slow... I usually create some kind of object, then paste it into the main model, and then just type in exact coordinates into the properties window to place it where I want it to be. But sometimes the view coordinates just disappear from the properties window, and I would like to know how to make them work again.

One of the examples would be:

- Create a 3d box

- subtract some cylinders from that box

the resulting object will not have x,y,z coordinates, neither width or height inside the properties window. Any idea how to make those properties work for this type of object?

thanks,

Karolis