Autocad 2005 problem

Hi,
I am facing a problem in Autocad 2005. When I open Layer Manager
propeties of certain drawings the computer hangs and I have to close it
from the Task Manager.
Another thing to note is, when i start a new document the problem do
not occur!
Also, if i open the same document with another version of Autocad, the
windo open normally.
This problem is also faced by other colleagues of mine who use the 2005
edition
Any propositions, please reply the soonest.
Regards,