Bios freezes up

So it works fine if you don't enter the BIOS ?
Anyway try updating your BIOS from Acer's website

Are the beeps posts or are they from you hitting to many button on the keyboard before it can respond?

If those are beep posts please go to this website:

http://www.pchell.com/hardware/beepcodes.shtml

You might want to try what Maziar has also said just do an update or give us the Acer's full name and series number and we can try to help you find a BIOS update for it.

Can you get into Windows or re-install Windows?

it works, but before it starts working it gives a continue beep sound for like 1 minute before it now boot to window.  

i can't re-install, because my boot sequence can not be change since i can't enter into the bios. some time i get into window after 1 minute of continuous beep sound.
the full name of the acer laptop is TRAVELMATE 415O

Possibly faulty hardware/Bios update. I will look into this further though for you.

Man this may sound stupid but I had an HP that I worked on for a week turned out to be a keyboard failure. Sometimes they will boot sometimes not. Try removing the keyboard and adding a usb keyboard see if the beeps go away. Usally caused by a stuck key. Give it a shot hope it helps.

Also a bad drive can cause this remove everything not needed cdrom keyboard touch pad and see what happens. Start adding back if it quits and see which one causes the issue to return. Beeps are telling you what is bad but acer will never tell you the beep codes so your on your own. Shout back if you need anymore help.