Vax 11/750 strange occurance

[utzoo!decvax!duke!chico!harpo!utah-cs!thomas]

I have recently run into a wierd occurance.  A large program is core dumping
with some regularity at a calls instruction where, as far as I can tell from
the core dump, it has no call to dump.  The exact instruction is
	calls	$1,*0(r11)
where r11 has a valid address, as does 0(r11).  Now, the strange thing here
is that this instruction begins 4 bytes before the end of a page (0xe5fc,
to be exact, but I don't think that matters).  When I mung the source so
that it starts elsewhere, I don't get the core dump (at least, not yet).
Anybody got any ideas?  (This is on a VAX 11/750).

=Spencer Thomas (harpo!utah-cs!utah-gr!thomas  thomas at utah-20)