xgterm out of ptys?

[Gordon Campbell]

I've just run across a problem that I need to fix for my department head
ASAP.

He's planning to use an astronimical image processing package called IRAF
that  relies upon xgterm for funtionality. The problem is that when you
try to run xgterm on his machine it hesitate, then reports that there are
"no more available ptys".

I'm completely stumped by this and haven't been able to find anythint
recent to help. He's running Core 2, completely up to date, on a Dell
Inspiron 8200. I checked my desktop machine, also running up to date Core
2, and it has the identical issue. Two other Core 1 machines don't have
the problem.

I'd be most grateful for any information or pointers. Thanks.