Compaq labtop onboard memory gone bad.

I just purchased a Compaq presario 12xl125 labtop. Labtop kept blue screening in windows 98 constantly. Received restore disk from compaq. Reformatted everything. Finally tried installing linux. Linux install gave me message that onboard memorywas failing. How can this memory be replaced? Can it be disabled? i have 256k of memory in expansion slot but still have error message. Any advice would be appreciated.