In *shell*, what *might* cause ^c^z and ^c^c to not work?

Something has changed, and I don't know what it is --
except that I'm now usisng Solaris 9.

(And I believe that that (moving to sol 9) is not the
problem, because I did that four or five months ago,
and only recently (in last month) started noticing
the problem.)

Anyway, when in *Shell*, and want to control-z
out of a program running there, C-c C-z doesn't
work -- nor C-c C-c, either.

Is probably same problem I reported a couple of
months back, and no one had any suggestion --
well, it's still happening, and maybe this two
months later, someone *will* have a suggestion...

Thanks,

David