Chi Nam,
<< it gave me an INVALID NORMAL ARRAY Fault. >>
It sounds like your 3DS.EXE got corrupted somehow. First, check your system
for virus' that might've "touched" the program, and then delete your 3DS.EXE
and reinstall it from the original master disks, making sure that nothing
modifies the program in any way. If the problem continues after that, contact
your dealer for a new set of disks.
jonas[adesk]
Sometimes my 3ds file gets corrupted and the only problem is if I Zoom
extents in the lofter, every thing locks up. Copying a good 3ds file
over it always fixes the problem.