On Feb 4, 2013, at 20:12 , Christian Wagner <christian_r_wagner@yahoo.co.uk> wrote:
* (setq q (make-queue))

(((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
[...]
debugger invoked on a SB-KERNEL::CONTROL-STACK-EXHAUSTED:
  Control stack exhausted (no more space for function call frames).
This is probably due to heavily nested or infinitely recursive function
calls, or a tail call that SBCL cannot or has not optimized away.

This is because SBCL is trying to print a circular structure. If you set *print-circle* to t, everyrhing should be ok:

* (setq *print-circle* t)

T
* (make-queue)

#1=(#1#)