Help With Hp Pav. 7935

[allstetic2]

I Purchased This Computer In 2001 And Then Bought A New One A Year Ago So The Hp 7935 Sat For A Year In Perfect Working Condition. Just Brought It Up For My Daughter And Now The Volume Mutes And Unmutes On Its Own. Can Anyone Tell Me How To Fix This ? Hp Said To Change The Bios Settings But I Still Cant Get It To Work Right. According To Their Configuration It Has A Sound Card And The On Board Audio Should Be Disabled. Please Help