G729 code causing Trixbox to crash - AMD Sempron CPU

Some words of advice are sought
I have a new AMD Sempron based box loaded with the latest production Trixbox.
Having bought two G729 licences from digium and followed the install instructons to the letter, Asterisk stops after the ‘restart now’ and will not start again until I rm the g729…so file.
I have tried most of the standard build files from the ftp site - even a couple of the 1.4 version althogh the Trixbox build maintains it is 1.2…
Using the asterisk -v command to start the app always falls over during the g729 phase so I’m pretty convinced somewhere I have an issue installing the codec.
(My older A@H box (v0.6) works nicely with its G729 codec (and separate licence) but it is Intel based.)
I’m no linux guru but I can make may way round if I have to (a prior life working on VAXen does that to you :smile: