First, try updating to the current build. The one you have, 19.0.67, is the current "stable" build (available on the download page), but this is not the
latest one (and it is actually quite old at this point). The most recent public build is 19.0.100, and that is available here in the "sticky" thread at the top of
the main MC19 board. MC has two different "auto-update" modes: Latest and Stable. The Stable build is updated infrequently and is better tested, but doesn't have all the latest fixes. The Latest one has gone through the Beta Team, though sometimes only for a day or two, and is less well tested, but is always the most up-to-date one. There are generally new "Latest" builds released once per week or so.
You can leave it set to Stable, so that it doesn't bother you to update constantly, but if you have trouble, step one is to come here and get the latest version (or set the auto-updater to check for it automatically).
Assuming that doesn't help...
Where are the files stored?If on a Network Attached device of some kind, this would point to a network issue.
If on a local disk, I'd check the disk for corruption.
It could also be an issue with the settings for your DAC, though I'm not super-experienced in this area, and I'd probably check into the file availability first.