A Graphic Problem ?

I run Win98, on a fairly elderly machine which usually works well. Recently, the old dear has refused to start occasionally. The power light comes on, and the HD spins, but the keyboard & mouse are not initialised. When it is working normally, itworks perfectly. But now and again it will not start at all. Switching off and then on again has no effect, but if I switch on and leave it in this “comatose” state, it will sometimes fire up later (in its own good time).
I am advised that my graphics card may be faulty, or about to fail. Anybody got any better ideas?