What can be done about the Windows 98 region code?
There are two versions of the Windows 98 region code. The first came with the original Windows 98, once you would erase the region key, it would regenerate with the next disc played. This would mean that erasing the windows key would reset the region counter (and could be done as many times as required).
This was changed with Windows 98 Second Edition. Here, the key is only created once, and once erased, it will not regenerate. This will cause any player relying on the Windows region key to stop functioning.
With version 3.75 of DVD Genie, you can recreate and reset the Windows 98 Second Edition region key, this will disable your old key, and create a new one from scratch. You can also manually specify the region directly.
If you don't want to take the risk with DVD Genie, the only way to bypass the internal region protection within Windows 98 Second Edition is to export (save) the current region code. Then let windows change it to a new key when required, and when you want to reset the region code, you import (load) the previously saved key.
Even if using the older Windows 98, it is recommended to export the region key for backup purposes.
Small note: the Windows Millennium Edition's region system, works exactly the same as the Windows 98 Second Edition, so you can apply the same methods.