I'm currently testing HFS under old OS again, and will document my findings here:
This is not a support request topic, we all knew the day would come. But it will be found through the search facility.
Windows NT4: HFS 2.3 beta build #180 broke compatibility with NT4, last working: #179
(I guess it's because of the 'Prevent standby' option).
Error message of #180(translated): 'Procedure entry point 'SetThreadExecutionState' could not be found in the Dynamic Link Library "kernel32.dll".'
Build #181-#183 fail to start silently (without error message) Use build #186, it works.
Windows 95C: Last working build is #179, all other builds behave exactly the same as on Windows NT4. Build #186 works again.
Windows 98SE: HFS 2.3 beta build #183 appears to work flawless. I guess ME will work, too.
So, the older OS are out cold now.