asterisk users - Jul 2008 - Asterisk 1.4 restarts after parking using AGI

Hi,
every time I park a call, my Asterisk box restarts.
This happens during calls made with AGI (not with normal Dial command).
Seems to be an Asterisk 1.4(.17) problem since my Asterisk 1.2(.18) 
works fine.

Anybody got some hint?

Thank you!

Giorgio