Hi, it could be that DOS 7.x and the Win 9x GUI see two different HDD geometries.

DOS uses BIOS to see HDDs, while Win 9x uses a Protected-Mode driver (similar to FastDisk in Windows 3.1).

If the HDD is controlled by DOS only for some reason (the PM mode driver fails), this compatibility warning will be seen.

It's not the only cause for this warning message, though, I suppose.

Jo22 wrote on 2023-01-15, 08:21:

Hi, it could be that DOS 7.x and the Win 9x GUI see two different HDD geometries. […]
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Hi, it could be that DOS 7.x and the Win 9x GUI see two different HDD geometries.

DOS uses BIOS to see HDDs, while Win 9x uses a Protected-Mode driver (similar to FastDisk in Windows 3.1).

If the HDD is controlled by DOS only for some reason (the PM mode driver fails), this compatibility warning will be seen.

It's not the only cause for this warning message, though, I suppose.

How could I see if this is an issue and fix it if it is.

MBR virus may cause this.

verysaving wrote on 2023-01-16, 02:23:

MBR virus may cause this.

Don't really know what kind of "MBR virus". That thing was often mentioned a long time ago, when my old PC was still using Win95.

Back then, once in a while I got a warning saying some "virus" changed the MBR and something, and told me about the system being in "MS-DOS compatibility mode"...

I was too young at that time to even know what a MBR is. At least there are some DOS-based antivirus software that could correct the MBR provided I boot the system using a clean floppy.

Not really sure how such viruses would manifest... as I never had internet access until much later and many such occasions predated that. While I cannot rule out the possibility of some files on CDs being "unclean", the virus issue could sometimes happen without any external input... so it may also be due to corruptions that Windows perceive as being abnormal.

Honestly, disk corruption was not uncommon during that period -- a system that's running perfectly fine today could suddenly stop booting the next day requiring a system reinstall.

LSS10999 wrote on 2023-01-16, 05:34:

Don't really know what kind of "MBR virus". That thing was often mentioned a long time ago, when my old PC was still using Win95 […]
Show full quote

verysaving wrote on 2023-01-16, 02:23:

MBR virus may cause this.

Don't really know what kind of "MBR virus". That thing was often mentioned a long time ago, when my old PC was still using Win95.

Back then, once in a while I got a warning saying some "virus" changed the MBR and something, and told me about the system being in "MS-DOS compatibility mode"...

I was too young at that time to even know what a MBR is. At least there are some DOS-based antivirus software that could correct the MBR provided I boot the system using a clean floppy.

Not really sure how such viruses would manifest... as I never had internet access until much later and many such occasions predated that. While I cannot rule out the possibility of some files on CDs being "unclean", the virus issue could sometimes happen without any external input... so it may also be due to corruptions that Windows perceive as being abnormal.

Honestly, disk corruption was not uncommon during that period -- a system that's running perfectly fine today could suddenly stop booting the next day requiring a system reinstall.

I installed Windows 98 SE on a newly formatted disk drive and after installing the chipset drivers for my motherboard (Asus CUSL2-C), I get the compatibility mode issue. This seems to be happening with the Motherboard Storage controller and the default storage controller which are causing resource conflicts plus, I can't remove any of them since they just come back when removed.

To clean the MBR just boot from a clean floppy and type FDISK /MBR, assuming you have just one HD.
But reading that the problem occurred after installing the chipset drivers I suppose that a virus
it's not the cause of the issue.
You may try restoring an old registry configuration booting in DOS mode and using
the command SCANREG /RESTORE and the selecting an older backup.
Windows keeps up to 5 copies overwritting the older one, so I suggest to make a copy of the
folder C:\WINDOWS\SYSBCKUP where the backups are actually stored before doing it.

Here's a better explanation : http://www.helpwithwindows.com/windows98/start-145.html

verysaving wrote on 2023-01-17, 01:45:

To clean the MBR just boot from a clean floppy and type FDISK /MBR, assuming you have just one HD. But reading that the problem […]
Show full quote

To clean the MBR just boot from a clean floppy and type FDISK /MBR, assuming you have just one HD.
But reading that the problem occurred after installing the chipset drivers I suppose that a virus
it's not the cause of the issue.
You may try restoring an old registry configuration booting in DOS mode and using
the command SCANREG /RESTORE and the selecting an older backup.
Windows keeps up to 5 copies overwritting the older one, so I suggest to make a copy of the
folder C:\WINDOWS\SYSBCKUP where the backups are actually stored before doing it.

Here's a better explanation : http://www.helpwithwindows.com/windows98/start-145.html

Didn't really make a difference, still have the chipset drivers issue. At least I don't have to reinstall windows whenever I have an issue though.

Try running my antivirus, it's portable and no need to boot from clean floppy as it can disable the virus and clean the MBR if it's indeed infected, chances are it will detect most common boot viruses of DOS days

You may try unistalling the chipset drivers and see if it makes any difference.

Masaw wrote on 2023-01-17, 04:33:

Try running my antivirus, it's portable and no need to boot from clean floppy as it can disable the virus and clean the MBR if it's indeed infected, chances are it will detect most common boot viruses of DOS days

No viruses found when I ran the check, I suspect the issue is a driver or windows issue.