Boot Problem - F1 Key

Yesterday windows flashed an error on Hard Disk Failure and told me to backup my files. Today, when i started the computer it just got hanged over BIOS menu.
I tried changing the SATA Ports and changing the boot order, but no use.
At last when I plugged everything back in place and tried to somehow make it work, by accident i discovered that the windows starts only if I press F1 although in the BIOS menu nothing displays that tell me to press F1.

So can anyone help me to fix this problem. I need to change it back to normal, that the windows should start normally without pressing any button.

Sure Ztruker, I first thought that the CMOS battery should be down, but nothing is displayed telling me to press F1 or any thing else. I accidentally discovered it. Ofcouse the data and time is set correct.
Thank you for your reply, i will try changing the battery.

If you received a message clearly stating your hard drive is failing and to back up your data, then I would do that immediately. Why argue with it? Is the message not clear enough?

You can confirm the HD's condition by running the maker's HD Diagnostic
extended CD scan followed by Disk Check

Yeah, i took a backup but the windows starts only when i press F1 every time in the boot screen, although nothing is displayed telling me to press F1. I should try Ztruker comment by changing the CMOS battery.

Thanks everyone, the CMOS battery was the problem to all this. After replacing this the computer booted automatically without pressing F1.