compile mode never finishes

[J. David Boyd]

I have emacs 21.3.50 running on three platforms: 

1. Gnu/Linux, works fine
2. Windows XP with Cygwin version, works fine.
3. Sco Unixware, compiling never finishes.

By this, I mean that, yes, the compile actually finishes, but the
"compile finished" (sp?) marker never shows up in the buffer, and the
'compiling' tag is never ever removed from the mode line.

I would like some direction as to how to debug this.  I saw someone's
comment the other day on freenode, I believe, about some setting that
matters for ttys vs ptys, but I can't recall it, or find any reference
to it in the emacs docs.

Any ideas on how to solve this, or do I need to somehow attempt to
debug through a compile session and see what is missing?  This would
be low priority, as it works, it just doesn't know that it worked.

Thanks,

Dave in Largo, FL