So my game runs perfectly fine, no crashes, I can load any save.

But I can't add new saves, neither manually nor by quicksaving.

Obviously the game's unplayable like this, because after I quit I have to restart from the save I had before Win 10!

I tried the fix mentioned in another thread (deleting the FO3 file in MyDocuments etc) but that didn't work.

I also tried deleting older saves, but still the same.

It's as if my hard disk is write-protected.

Any help please?

OK I found the fix. Hopefully this might help somebody else...

First install from here:

http://www.tenforums.com/tutorials/3841-take-ownership-add-context-menu-windows-10-a.html

Right-click on your MyDocuments folder and select 'Take Ownership'.

Run FO3 as an administrator.

I believe you can do this without using a program.

Likely the documents folder was set to read only.