You say that you have reloaded the machine, the first thing to do is too:
Load windows 98se in safe mode, you will probably have to navigate using the keyboard as there will not be a mouse!! Use your tab key to highlight my computer. Once this is done press the key which looks like a menu on your keyboard (Usually 3rd key from right hand side of space bar) and select properties from the pop up menu!!
Use your arrow keys to open up the "Device Manager Tab" where you will most probably find some of the items with either a red cross or an exclamation mark.
Go through each one selecting properties, and installing the correct drivers for each. You may be prompted to resart your computer after each one, if the computer fails to start after installing a driver simply use the safe mode and go onto the next using the above proceedure.