2005 Weirdness

I inherited a 3D drawing from someone in the office who did something weird
with the layers. I edited an existing xref and inserted a new one. I had
previously set up some perspective views. The first time I switched to one
of the views, the xreffed buildings were visible for a moment, then
immediately disappeared from the screen. They were also invisible in plan
and iso views. I have a workaround -- reinsert the xrefs (thank God for the
old DOS commands-- -xr r Enter). Even so I have to turn on a layer in one of
the xrefs each time. Not only that, this will only work if visretain is
turned off.
Anyone have any insights?