Running win98SE. On boot up there is a rapid clicking from (I think) the case speaker, but difficult to pinpoint. When desktop available any icon I click only "blues up" the bottom one of that particular column. I have to activate all the bottom ones before I can use the one I want. I thought perhaps it was the H/D but changing that has not changed the situation. Is it the mobo or something else? Or there any other checks I can do. Grateful for any help on this.