I use an axiom xterm (with or without clef) :

  123_[return]456 has a right result but a wrong display before.
  I only see 123_, not 123_[newline]456

  123_[return]+456 has a right display and a right result.
  I read 123_[newline]+456

  The display is also wrong when I make a little file with
  123_[return]456, and I read it.

I use the Axiom 3.0 Beta (February 2005) in a linux box.

This also seems to happen on MathAction

123_

(1)

123_
+456

(2)

But the display and results are correct in the Windows version.