Problem Harddisk when turning on

Hi everybody,
hope somebody can help because I have no idea...
So, we were on holiday and before going on holiday we switched off the main switch on which all the computer cables were plugged (computer surrond syst, etc...).
Coming back when turning on the first thing was a black page saying smth about some errors (no I am sorry that I didn't look closely to the error message...smth with error check summ) and giving be the possiblity to press F1 for continuing , which I did... afterwards nothing happens, Windows tries to start, it gives me the possibility to start in safe mode or normal mode but whatever solution I choose completely shuts down the system and it restarts with a message saying no IDE found, Drive 0 not found, drive 1 not found, drive 2 not found...

The BIOS recognizes the name of the harddisk (a seagate 120GB) but there is no possiblity of booting the computer, not from the CD or otherwise...

Do you have any idea what might have cause it and how to repair it? Until the last day the computer functioned absolutely ok, with firewall and anti-virus with the last virus defintinions...

Thanks a lot,

Checksum error during POST usually indicates a dead BIOS battery. You won't know it's dead until you shut the computer down and unplug it... which is essentially what you did. Just go to the CMOS setup and reconfigure your settings... make sure your hard drives are being detected.