Ive replaced my laptops hd and this message come out while booting sd2 partition signature not found. What does this mean?

It might mean the BIOS can suspend to disk, but requires a special partition to do so. Then again, it's all a friggin guess without more details.

youre right about suspend to disk , But how do I make the copy for that partition?

You mean, how do you make that partition on your laptop? Simple, use the Acer utility. It doesn't matter if you have a Toshiba, Lenovo, Dell Gateway, Sony, or other laptop. The Acer utility will work for all. If you want better advice, try asking better questions.

If you want to copy your entire old HD to the new HD, Norton Ghost can probably copy the secret partition, but it might not work right. Best way is to use the utility for your specific lapto... I mean, the ACER utility.