AcerLigt Notebook

Hi There I recently aquired a older AcerLight Notebook with a faulty hard drive. I replaced the hard drive and loaded windows 98 first Edition. When the computer starts up the writing on the screen uses the corners of the screen but when windows logo starts it only uses 3/4 of the screen leaving a 1/2" black border all around even when windows has finished loading. I have looked in the display settings and this cannot be altered. I cannot seem to find any way to strech windows to use the full screen. The notebook is a pentium 133 Mhz with 640 Base Memory 48128 Kb Extended Memory and the Display Adapter is a Chips & Technologies 65550 pci. Hope one of you brainy chaps out there can help. Kindest Regards Tony B.