Thanks Hood
I finally got the thing working.
First I stripped Vista down to the bear min, That didn't work.
Next I Installed 3.039, every thing worked great.
Being a stubborn person I had to try 3.043 again still no pleasure.
Next I uninstalled Mach and all components of it plus deleted the directory.
Reinstalled 3.042 and it worked.
There must of been some files that weren't getting upgraded, because the paths in the tool path window look a lot nicer.
It does take about 4 min longer to generate the tool path than 3.039. 4 min 11 sec compared to 46 sec.
Thanks for your help, much appreciated.
Barry