hey friends I also had the same problem with my Acer 4736Z model ... and i did the same thing as deskdecode Said .... Changed the bios config. from "AHCI" to IDE .... it worked ... thankx to deskdec .....
As i dnt knw much abt the computer, can u guys make me clear that, is it a virus Which is doing the transition of BIOS Setup from IDE to AHCI ... (Which We have to restore to make it working normally)
What is IDE or AHCI ..... Which use to be the default setting .... ... ???
Changing the setup from AHCI to IDE have removed the problem ....