My sound keeps going to the top

[cundiff11]

Hi, i have windows vista home premium 32 bit. my computer volume, i am using the laptop speakers, keeps going to 100%. when i click on the volume icon in the bottom right, and i drag it down, it just goes straight down to the top. i ended up going to control panel and volume settings and then clicked balance, and had to individually change the right, left, sub, tweeter, and center indiviudally. anyone know what may be causing my problem? i also restarted my computer. no avail