really strange crashed PC

Yesterday morning i hit the start button on the PC and it started loading,then came the message we all dread "please insert disk", not knowing why i started looking for the problem, after 4 hours of trying everything including using a boot disk i could not get the beast to fire up so i made the ultimate decision to re-format as i had backups of all my important stuff.
When i get to the point where it asks which disk to install the OS on, i select "C" where the original OS was but it tells me it can not install on the disk because "it does not have the criteria to allow the installation" so i try another disk, same result and all 5 HDs in my PC give the same result.
I used Hirens Boot disk to get into the disks and Formatted them but still it will not let me install an OS on any of them.
After hours of frustration i opened the tower and removed all the disks and used a spare new disk that i had, the system installed perfectly on that disk.
Not being super PC savvy i can only assume that the bootloader for the disks had disappeared.
I replaced the original disks and formatted them all and now they appear to be OK but i have no idea what happened because i turned the PC off the night before and all was well but overnight all that changed.
I am now back up and running so i am a happy Bunnie.

Any ideas as to what happened ??

 

Not sure about updates as they install after shutdown.

As for bios nothing was changed in there.

 

What happened is that it is a computer! :wave:wave:wave

Sometimes, and I find myself saying this all the time, God, I've never seen that before!

 

I have been searching deeper into this problem.
I bought the latest Paragon disk manager and found that all the disks in the PC had no boot manager so i have installed it on them and now i am able to install my other OS on any of the disks.

I have still not managed to figure out what caused the problem?????