> I confirm also that the current ZTW_CFG.EXE will not run in 32-bit XP.
> Alt-F10 fails, and when run from the command prompt it gets the message:
> "ZTW_CFG.EXE is not a valid Win32 application." This started with
> v2.4.208. I suspect that the current ZTW_CFG.EXE is 64-bit only, but I
> have no way of confirming it, as I have no access to a 32-bit Windows
> later than XP.

have at hand the distributed Zeta archives back to 2.4.202 ...
extracted all ZTW_CFG.EXEs + run Sysinternal's sigcheck over them.
the verson numbers are different between ZTW_CFG.EXE + ZTWxx.EXE ...
ALL report to be 32bit EXEs ...

ztw24202:
ZTW_CFG.EXE : 157'880
Signing date: 2018.03.20 02:34
File version: 2.4.183
MachineType: 32-bit

ztw24203, ztw24204, ztw24205:
ZTW_CFG.EXE : 162'536
Signing date: 2022.05.11 01:50
File version: 2.4.203.0
MachineType: 32-bit

ztw24206, ztw24207:
ZTW_CFG.EXE : 162'520
Signing date: 2022.12.22 02:16
File version: 2.4.206.0
MachineType: 32-bit

ztw24208:
ZTW_CFG.EXE : 212'184
Signing date: 2023.02.06 04:12
File version: 2.4.203.0
MachineType: 32-bit

ztw24209:
ZTW_CFG.EXE : 215'256
Signing date: 2023.03.16 03:09
File version: 2.4.209.0
MachineType: 32-bit

ztw24210:
ZTW_CFG.EXE : 213'208
Signing date: 2023.03.18 16:56
File version: 2.4.210.0
MachineType: 32-bit

ztw24211, ztw24212:
ZTW_CFG.EXE : 223'448 (2023.04.18 20:45!)
Signing date: 2023.04.19 02:45
File version: 2.4.211.0
MachineType: 32-bit

ztw24213, ztw24214, ztw24215:
ZTW_CFG.EXE : 223'448 (2023.05.17 21:28!)
Signing date: 2023.05.18 03:28
File version: 2.4.213.0
MachineType: 32-bit

guess only KIM knows more ...
HTH, andreas