The reason that pulling the battery doesn't work is that, on laptops, the password is actually stored on an EEPROM chip, not in CMOS. This is probably the case with your laptop. As a result, using a tool like cmospwd is a bad idea, as you can brick your laptop permanently.
That being said, there may still be some hope of recovery. Acer laptops (some of them) have either a manual reset switch or jumper on the motherboard that can clear the EEPROM password. You'll need to disassemble your laptop and go over the whole motherboard (both sides) to look for a switch. Flip it, put the laptop back together, set a new password, open it up again, flip the switch back, and put the whole thing back together again. Then you can input your newly set password to get into the BIOS to finally disable the need for a boot password. The first place I'd look would be under the keyboard.
Whew. That may get you your laptop back.