I upgrade an old 2011/2012 MacBook Pro to high Sierra so I could download the latest Xcode. there has been a few times since then that the machine will freeze

I upgrade an old 2011/2012 MacBook Pro to high Sierra so I could download the latest Xcode. there has been a few times since then that the machine will freeze then show a folder with question mark icon. surprisingly it boots up fine after turning it off and on again, but I'm worried it won't last long. its a bummer b/c even though the machine is old, I upgraded to 8gb of ram and 500gb ssd and the performance is comprisable to a new MacBook a just got.