I repeatedly need to reinstall Mac OS

Indyspudman wrote:

Over the past year, and on two successive MacBook Pros, periodically the log-in password becomes invalid (not recognized during log-in) and the only solution is to re-install the Mac OS and all my files. This is only happening on my MacBook Pro, not on my wife's MBP or my iMac. Any idea how to figure out the problem?

Seems a bit odd—

See what Apple Support has to say:

Call Customer Support (800) MY–APPLE (800–692–7753)

or

on line Apple Support

One possibility (perhaps a remote one) is that some third party software is somehow managing to corrupt the password. It might be useful to see what is installed "under the hood" and compare to what is installed in the computers which do not have this problem. A good start on investigating this would be to run EtreCheck and see what it reports. Give it Full Disk Access. You can post the report here. Someone might spot something.

Remove BitDefender and Malwarebytes using their maker's instructions.

You have a lot of out-of-date plug-ins going on there. Remove the Wondershare iTunes helper, Flip4Mac (not developed in years), LOgMeIn 32, Log Me In Sadfari32, Silverlight and iPhoto Podcast (strictly historical interest only...) I would also remove the Garmin software which can be reinstalled later if you require it.