This is easily fixable.
You always need to load the chipset drivers for your mboard after a fresh install of any operating system, because Windows may not be able to identify everything on the mboard automatically and install drivers for it, often because the mboard or chipset did not exist when that version of Windows was released.
That should make your problem go away.
If you have the CD that came with the mboard, the drivers are on that, as well as drivers for anything else built into the mboard. the Install screen will usually auto start when you insert the CD and Windows is already running.
If you don't have the CD, you can go to the Intel site and get at least the chipset drivers. If you go to the right place, your chipset can even be detected if you don't know what it is. If it is a genuine Intel brand mboard (not one of the zillion ones that are made by others that use Intel chips), they will have all the drivers for the mboard.
If the mboard is not genuine Intel, you must go to the website of whoever made the mboard and get all the drivers there.
..........
Other tips.
Install at least the Microsoft DirectX version your video drivers require. If you have the original CD for the video card, the install on the CD will often detect whether you have the correct DirectX Version and install it automaticaly - if not, it is often on the same CD for you to install. If you get updated video drivers, the DirectX version required often goes up. If you're not sure if you have the right version, get the latest one. For Win 98/98SE/ME, the newest DirectX version does not work in Win 98/98SE/ME - you must dig around the DirectX support pages and find DirectX 8.1, the last one for 98/98SE/ME, or find that version on the web.
If you have the video CD it will install all the drivers properly. If you allowed Windows to find the drivers on the CD while booting, and installed the drivers that way, it often doesn't install everything - run the install on the CD in that case.
Get the drivers for your monitor and install them. If you didn't have a lot of colors, or the resolution was restrcted when Windows first loaded, loading those will improve the situation, and you will be able to use all of the settings the monitor supports.
Use Windows Update to update your Win98SE, but don't install anything before reading the descriptions and deciding whether you really need it - e.g. I would recommend you don't install Internet Explorer 6. You should install all the Critical, Security, and most of the recommended ones.
You must go back to the Update site several times to install all you should.
If you don't like the idea of Windows Update installing all of that stuff in big batches, you can go here, choose the ones you want to install, download them, and run them one by one:
Download updates to install yourself (not all of them are there):
http://www.microsoft.com/windows98/downloads/corporate.asp
Windows Update then won't need to install as much.
THEN install antivirus software. It has been known to interfere with Microsoft Update in some cases.
