Strange noise when booting

When I boot my computer, at the very begining, the computer goes bip, bip, bip, bip, for about 30 secondes, then it continues booting normaly… it slows the booting a little and it’s anoying. I tried to reload the bios (using the flash bios on acer’s web site, but it didn’t change anything. I have an ACER 5110 that I bough 1 year ago, (warranty expired)