To check the knowledge base integrity, do the following:
In the File menu click Check Knowledge Base.
Adapt It does an immediate integrity check of the knowledge base.
Checking does not confirm things like spellings, but rather tests for things which might cause the knowledge base to become corrupt and so that Adapt It could not use it.
It is not a foolproof check; some bad things may escape detection.
If you are having problems with the knowledge base but the integrity check does not detect any errors, restore the knowledge base.
If the integrity check fails, Adapt It displays a message asking you if you want to substitute the existing backup file for the corrupted knowledge base. If you respond by clicking the Yes button, Adapt It throws away the bad knowledge base, renames the backup so that it becomes the current knowledge base, and opens this new knowledge base for further work. If the new knowledge base is also corrupt, restore the knowledge base.