Hl,
all development of Mach3 ceased five years ago in favour of Mach4.
Lots of people still use Mach3 and prefer it but as Gerry points out recent Microsoft Windows updates have broken Mach3.
There is a patch but really you will have to prevent your Windows OS from updating. There are NO updates for XP so that should be
safe.
Mach4 has no reported problems with updates and NFS is on hand to fix issues as they arise.
Craig