Vault stops adding

For no apparent reason, my vault (approx 50% full) has stopped adding new entries. Scanning routine is as normal, but no new entry is made to the library. How is this to be corrected? I normally have about 10% of new scans just disappear but now it is 100%. There are also another 10% who list as "ripped" with no title or track info. Where have these all gone and how do I retrieve them?