I turned my computer on one day after a few months of non usage and it came on to the logg in screen perfectly. Then I realised I hadnt plugged the keyboard or the mouse in, so I turned it off an plugged them in. It turned on and went to the acer screen and says press f12 to the setup page. So I waited for it to go on but it stayed there for hours. So I thought then ill press f12 but the keyboard wasnt working. There isn't anything wrong with the keyboard its just sometimes my computer dosent like it. I tried using many diffrent ways but nothing seems to work. I took everything out and just left the main and the screen in and it worked perfectly its only if the keyboard and mouse are in it it dosent like it.
I think it got annoyed with me because I didnt pay it attention! lol
make sure if you have a memory card or a usb drive plugged in that you remove it before it boots, also if you have external hd remove that, just in case
can't guarantee this is it, but its happened to me