Major glitch!??

I’d like to get an understanding of what happened yesterday. I closed down my machine and then rebooted. I may not have waited the 10 seconds that you’re supposed to wait on a re-boot. Right after the hardware boot cycle, when windows would normally begin to load, I received the following message on a dark background “DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER.” I powered down using the front panel button. This time I waited longer but the same result persisted. I tried this several times all with the same disk boot failure result. Then I went into the bios and found that only one of my three hard disk drives was detected! The system drive was one of the two that was not detected during the hardware boot cycle, ergo the disk boot failure. The problem persisted after a few more power downs and restarts as described above. Then I powered down and turned off my power supply using the switch on the rear panel of the supply. Waited 20 secs and turned it back on, booted up and the problem is gone!! I have no idea how to explain this. I’m concerned that something is intermittent or aging but don’t know how to determine what that might be. Can anyone provide any insight or ideas?

Rarely I need to power down from the PSU switch to fix an issue, it happens. You should be backing up your OS/data anyway in case of a failure of disks.

Thanks GokAy. Yes I do keep my drives backed up pretty regularly just in case. I don't think this is a disk issue though since only one disk in my system was detected. Two hard drives and one DVD drive were not detected during the hardware boot cycle as was seen when I entered the BIOS setup screen.
Any ideas as to what could cause such a problem?
Could the battery on the mobo do this if its getting weak?
Is my mobo developing a problem?