Raid 5 Rebuild Failure

RAID 5 ARRAY REBUILD:

I am trying to set up a RAID 5 array connected to my server which holds 3 WD drives. These drives are from an old server, and have important data on that I want to recover, which is why I am trying to recreate the RAID 5 setup. I thought that it would be an easy job, but I am struggling to get the RAID 5 array to rebuild itself. The rebuild begins, and gets a certain length along the process bar, and then the computer reports that one of the drives has stopped working. There is no consistency about which drive stops working, and so I am not able to work out where the problem is. I have tested each of the drives in turn, and they are all reported as normal. However, I am not able to extract the data except when the drives are set up in an array.

RAID 5 SERVER:

I have a PC computer with self-built RAID 5 array featuring 3 disks, as well as a separate operating system disk inside the computer. The array has been operating fine for the months that I have had it, but the OS disk would constantly fill the array with files full of computer gibberish. I have constant running battles to remove as much of the gibberish as possible before it fills the server, but I have suddenly lost the array, with all of the disks. I ran a couple of disk checks to try and resolve the problem, and one reports that the drives are normal, while the other says that the disks are unallocated. I have not been able to recover the array since then, even plugging it into another computer and trying to read the drives from there.