This started recently after I updated to 104,maybe a coincidence but not sure
This sounds like the hard drive is starting to fail, or if it is a USB connected drive something is wrong with the USB port/connection/driver.
To protect your settings in the library and avoid files being re-imported, change the configuration of Auto Import. i.e. Change the Setting "Fix broken links:" to "Yes (protect files on missing drives)".
MC will then show the files with a red circle with white line through it icon, showing they are not available when the drive isn't connected, and will fix that when the drive re-connects, without re-importing.
As for your drive, you need to work out why it doesn't connect sometimes. I use
HD Sentinel to monitor my drives all the time. Use that or something else to check the drive when it is connected, and if it is okay, then suspect the connection/cable. If it is a USB drive, perhaps try a different port.
If the drive is showing problems, replace it sooner rather than later.