Parallels Desktop 8 and Mac OS X 10.5 guest upgrade

Hello,

For our development needs, we need to have a virtual machine using OS X 10.5. The host is a Retina Mavericks.
Unfortunately if we apply the OS X 10.5.8 upgrade which comes naturally with the systems updates, the guest OS crashes during start-up. so we have to keep the bare OS but in this case the parallels desktop tools won't work

Any idea? (except upgrading, to potentially just realize that it won't work either)

EDIT: The problem is worst than expected, without upgrading to recent OS X 10.5 update, code signing certificate delivered by Apple don't work and the build chain cannot work.

EDIT AGAIN: I just tried with the demo version PD9 it does not work either, the even worst news is that your main competitor (VMW.. F...) fails flat the machine does not even start with the base OS.

Regards
Armel