sqlplus hangs on "set autotrace on"

sqlplus = 8.1.5
os = linux

"set autotrace on" hangs the sqlplus-process when I want to quit (or ctrl-d).
Both ctrl-c and ctrl-z gives no response. "top" in another unix-shell-window
reveals a very busy sqlplus-process, but it never finishes! I have to kill it
explicitly. Autotrace is a very nice feature, but this behaviour annoys me.
Any hints?

-- 
Kjetil Skotheim
kjetilskotheim_at_iname.com