[Ben Jenssen]

Hi. Could you provide the model number, or year. (Check "About this Mac).

I have an old cheesegrater myself, as I retired some years ago. Mac Pro 3,1, "early 2008", 2.8gHz xeon, with one "PT boot drive (10.6.8), and one "Everything else" boot drive (10.12.5). Both SSD's on PCIe adapter card.

I think the first thing he should do is to pull out the faulty drive and see if that fixes the shutdown issue. If it does, and the everything else works, there's no reason not to just buy a new 7200 rpm harddisk, they're cheap, and restore from Timemachine, like you said. No reason to buy an external drive, as replacing an internal one on these machines is very easy. Pull it out, four screws swap, and push it back in.

The last OSX version that will install on the 3,1 (if that's what he has) is 10.11. Anyway PT doesn't run on anything later than 10.8, so I see no reason not to just stay on 10.6.8. It plays very nicely wih PT10 in my experience.

A thing to consider is upgrading it with a SSD (or two) on a PCIe card. For, say $200 for the card and a fast SSD (I have OWC Mercury EXTREME Pro 6G) you get a 500mb/s read/write speed that really gives new life to these old macs. With system and apps on that kind of SSD, boot times, application launch, everything is three times faster than on the 70mb/s spinner HD's.

So, if he's happy to stay on an old OSX/PT system with almost no upgradability, there's no reason that mac can't work for years.