Reinstall 98SE by running setup with this switch:
setup /p i
There's a space between p and i.
It will disable screwed up ACPI implementation on 98SE, and might fix shudown issues.

Thank you. Is it possible to disable ACPI without reinstalling Windows? I am quite far with this installation.

Disable it in the computer's BIOS, then see whether Windows modifies its installation and can properly restart. You might have to start in Safe Mode to get it to do that.

I don't have any option to disable ACPI. There's only "ACPI Sleep Type" in "Power Management Setup" and there are only two options:
1. S1/POS
2. S3/STR

Try following these instructions:
http://www.mdgx.com/newtip15.htm
I've never done them, as I always install 98SE with the /p i switch.

Also, try removing some RAM, 256MB is enough for your rig. IF you can't, limit it by using MaxPhysPage switch.
Also, try removing your sound card, or other peripherals, maybe there's a conflict somewhere?

Caesum wrote:

Thank you. Is it possible to disable ACPI without reinstalling Windows? I am quite far with this installation.

Yes, it is possible, but it requires using the Registry Editor:

Start the Registry Editor Go to HKEY_LOCAL_MACHINE \ Software \ Microsoft \ Windows \CurrentVersion \ Detect In the righ […]
Show full quote

Start the Registry Editor
Go to HKEY_LOCAL_MACHINE \ Software \ Microsoft \ Windows \CurrentVersion \ Detect
In the right-hand pane right-click an empty space and choose New > DWORD Value
Name it ACPIOption, double-click it, and change the value to 2
Close the registry editor
Redetect System Hardware

The choice of options for the ACPIOption value are as follows:

0 (or not present) - Detect only ACPI BIOSes on good list
1 - Detect any ACPI BIOS
2 - Do not detect ACPI BIOSes (remove support if installed)

Note that you may see some sources (including the Microsoft Windows 98 Resource Kit: The Professional's Companion to Windows 98 from Microsoft Press) that indicate that ACPIOption is a String rather than a DWORD value. These sources are incorrect.

^ I have disabled ACPI with this registry and now my PC sees a lot of unknown hardware and it doesn't see CD drive. Also it cannot reboot now at all.

EDIT: Okay, rebooted again and it works fine, but shutdown reboots anyway.
EDIT2: If I wanted to reinstall Windows 98se - is there any pack of updates made for 98se? Also, how do I run SETUP with /p switch? Using DOS mode?

Caesum wrote:

^ I have disabled ACPI with this registry and now my PC sees a lot of unknown hardware and it doesn't see CD drive.

Since power management touches pretty much every piece of hardware in the computer, just about all of the drivers will be uninstalled and then re-installed whenever ACPI or APM is turned on or off OR when switching between ACPI and APM schemes. Sorry for the lack of warning, but it has been over fifteen years since i saw this in action for the very first time, and I had forgotten how startling it may appear.

With regard to your update pack question, I install updates individually (I squirreled them away years ago). Others use unofficial update or service packs, and there are threads on this board concerning that topic.

Also, I always make a point of copying the contents of the Windows 98 SE CD-ROM to C:/Win98 BEFORE installation and then run the install from there. This approach avoids having to re-insert the Win98 SE CD-ROM when drivers are needed at a later date. Once the files are copied, you can then run setup.exe with any desired command line switches.

akula65 wrote:

Sorry for the lack of warning, but it has been over fifteen years since i saw this in action for the very first time, and I had forgotten how startling it may appear.

Everything has reinstalled by itself so no worries, everything works now. Just not shutdown.
If after disabling ACPI my OS still cannot shutdown properly, does it mean there's something wrong with motherboard? Or Windows? Hard shutdown works fine(the one that you just push the button on your PC until it turns off).

akula65 wrote:

With regard to your update pack question, I install updates individually (I squirreled them away years ago). Others use unofficial update or service packs, and there are threads on this board concerning that topic.

I see there's a program called WinSPatcher 98SE that works for Polish version of Windows 98se. I'm thinking about trying this one instead of unofficial patches.

akula65 wrote:

Also, I always make a point of copying the contents of the Windows 98 SE CD-ROM to C:/Win98 BEFORE installation and then run the install from there. This approach avoids having to re-insert the Win98 SE CD-ROM when drivers are needed at a later date. Once the files are copied, you can then run setup.exe with any desired command line switches.

Sounds like a good idea, but this way I'm unable to format C: disk, no? If I was to reinstall Windows 98se I would have rather liked to start with a blank card to be honest. I want to avoid reinstall unless necessary.

I have taken out two RAM to get 256mb ram but now for some reason Windows 98se reinstalled some drivers, bluescreen happened telling me my COMPEX RL2000 Ethernet Adapter does snot work properly and that's it. Why 🤣

Caesum wrote:

Sounds like a good idea, but this way I'm unable to format C: disk, no? If I was to reinstall Windows 98se I would have rather liked to start with a blank card to be honest. I want to avoid reinstall unless necessary.

Create a Windows 98SE boot floppy, boot from the floppy with CD-ROM support, reformat C:, then insert the Windows 98SE CD-ROM and copy the files to the hard disk.

Unfortunately I don't have a working floppy drive.

Caesum wrote:

Unfortunately I don't have a working floppy drive.

Then maybe that should be the first thing you fix, especially on a Windows 9x system. 😀

Easier said than done, I have a different floppy drive which I could use, but it seems the PC box is made in such a way I cannot put any other drive. I didn't need it so far anyway since USB sticks were pretty good to work with W98se too.

EDIT: Oh I forgot to say the COMPEX RL2000 Ethernet Adapter works fine again now. Must have touched it or something when removing unnecessary hardware.