So here is what happened today. I was to unpack some PS3 games from my archive backup that I did a time ago. Difference between then and now is that then, I had i5-4690k and now ryzen 5800x. Exact same Win7 with just switched drivers, not reinstalled and working perfect so no issue there.
What happened is that ZTool would remain hanged on processes without using any CPU, therefore unpack would fail(infinite run). I was getting desperate but then I localized this issue to ZTool. Perhaps due to SMT but did not try turning it off in bios. Also, both HW and system is guaranteed stable and have nothing to do with it.
So then thinking about it, I got an idea to disable threading for ztool during unpack, so I put
option in arc.ini unpackcmd line. Well guess what, that did it! After this Ztool became perfectly reliable again. It also look like it is probably only needed during decompression, not compression but further testing would be needed.
Bottom line is that if you have older archives that were using ztool, you may need this on new system to be able to unpack! And at least you can still unpack, because of course, if you have those installers or older repacks... good luck. I don't use installers, I archive into 'arc' file using FA GUI and that saved me.
Btw, XTool do not have this issue.
UPDATE:
Option
as suggested by Gehrman seem to be even better way, giving back speed of multi threading without consequences. Thanks!
EDIT: Disabling SMT in bios did not help, above option remain the best solution. For repacks, you should be able to unpack setup.exe with UniExtract2 from github, but to go further on how to put things together to be able to install repack, I have not explored yet.
PS: You can still get an error during unpacking sometimes, just try again as it can be flaky for some archives, however second time you may get a strange error of access/permission deny(despite being admin account), so either unpack another archive(to "reset") and then try problematic one again, or restart whole PC first.