After doing a bit of research into some problems with a DMS not being fully usable when PhatHack Media Manager generates the PhatBox data files, sbingner managed to find the fault lying in the PhatSig.dll code which was an EXACT port of the code lurking around the WIKI.
As a result there'll be a version 2.6 of the tools coming up which should solve any problems with people's hack not running. This is likely to manifest itself with the phatbox constantly rebooting.
As part of the identification/fixing of this code I've also created an application available under the SVN project name 'winplsign' which is a standalone windows version of plsign.
You can download and use a compiled version of the application
here to generate any SIG files you need to. If you a suffering from the above problem trying to run the hack, then point the application to PHTSYS\exec.ini. You can do this directly on the DMS.
Sbingner did some tests of the signing code under x64 and that seems to be working as it should too!
A big thanks to sbingner for helping identify, and more importantly solving, this one!