Script for Maya that deletes reference nodes that have been mysteriously corrupted (not showing anywhere, not pointing anywhere).

del_corrupted_refs.py

import maya.cmds as mc

refs = []
message = 'No corrupted references to delete.'
for ref in mc.ls(references=True):
    try:
        mc.referenceQuery(ref, filename=True)
    except RuntimeError:
        mc.lockNode(ref, lock=False)
        refs.append(ref)
if refs:
    mc.delete(refs)
    message = ('Deleted the following corrupted references:\n'
               + '\n'.join('\t'+x for x in sorted(refs)))
if mc.about(batch=True):
    print message
else:
    mc.confirmDialog(title='Delete corrupted references', message=message,
                     button='OK')