Two failures like that would make me very suspicious of a deeper problem with your boot volume. If it is a rotating rust drive I would run a full surface scan. If it is ab SSD I would take a close look at the detailed S.M.A.R.T. report. Unfortunately I only know of one app that provides either report — TechTool Pro 11.

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein