If I remember correctly, your "new" machine is very old. It is likely that current advice and rules of thumb don't apply. Perhaps your power supply is dying of old age. Fans certainly wear out. Having too many things in your box might stress your power supply. Three disks seems like a lot for a DOS setup. Is the problem that DOS can only handle small drives? The more things in your system, the more points of failure. I imagine that, sooner or later, you are going to have to move to a newer platform. I know you already know how hard it is to stay with the technology you have. I don't have time to review what you've said about your system, but I seem to remember that you are very attached to your Kurzweil Reader and that Linux's screen readers are not good enough. So I know that replacement isn't easy.