I don't know why X1 needs you to unlock these files, but making them read only strikes me as an odd thing to do.
If you are worried about these files becoming corrupt, then locking them might actually make the problem worse. If Windows cannot itself check and get at files, what happens when you have a disk problem that corrupts the file? (Disks don't last for ever.) Perhaps also you do not do anything to "defrag" your files.
I also keep a lot of material in archived PST files. To protect these from damage, I do what I do with all important files. I maintain backup copies – and more than one of them – in safe places.
If these are the only copies of these PST files, then you run more chance of losing them if the hardware fails than if X1 zaps them. If these really are archived files that will never gain any more data – mine grow as Outlook archives old messages – then burn copies on to a set of DVDs or put them on spare hard disks. In that way you can allow X1 to work on them safe in the knowledge that you can recover if the worst happens.
If you are worried about these files becoming corrupt, then locking them might actually make the problem worse. If Windows cannot itself check and get at files, what happens when you have a disk problem that corrupts the file? (Disks don't last for ever.) Perhaps also you do not do anything to "defrag" your files.
I also keep a lot of material in archived PST files. To protect these from damage, I do what I do with all important files. I maintain backup copies – and more than one of them – in safe places.
If these are the only copies of these PST files, then you run more chance of losing them if the hardware fails than if X1 zaps them. If these really are archived files that will never gain any more data – mine grow as Outlook archives old messages – then burn copies on to a set of DVDs or put them on spare hard disks. In that way you can allow X1 to work on them safe in the knowledge that you can recover if the worst happens.