I recentley ran into this problem where sometimes my mobo can't detect my system hard drive. It seems to happen when I leave the pc on for a long time. like a day or so. I have woken up and the screen says cannot detect system disk in the boot up sceens. I then turn it off for a few hours and then it boots up fine. The hard drive is around 5 years old. Its a seagate 160 gig. I bought a new HD to act as media storage and I set it to slave. could the new hardrive be effecting the old master drive that is failing? I am not sure but I think the rpm's are the same on both drives. Would that effect it? If anyone could offer input I would greatly appreciate it. Thanks in advance...
I would first check if its not a power usage/monitering problem.
make sure in the Power options That the harddrive isn't destined to shut off after any amount of inactivity.
Other then that I would back up all important data just in case it does die.
There are are few bootable tools like Symantec Ghost and UBD that can scan a harddrive for problems.
Theres also HDD Health that will show you while in the OS of any problems.
HDD Health is Free and so is UBD. (Ultimate Boot Disk)
The UBD will be .iso Format so youll need to burn to a blank disc as an Image (Using Nero or DVD Decrypter, or whatever program you use.)
Just google them.