Sharif,
If it was me I would format the hard drive and reinstall Win98. With use Windows hogs up lot of hard drive space and leaves files no longer needed. By doing a fresh install you computer should get a new life and function better. I would install Windows second edition as it is more stable. Here is a link to further investigate : http://support.microsoft.com/default.aspx?scid=kb;en-us;259181
My 2 cents and best of luck.