The disk-quota on a username/disk can get out of synch.

To test for incorrect disk-quote do a:

$ DIR/SIZ=ALL/GRAND disk:[user...]
Grand total of ? directories, A files, ?/B blocks.
$ DIR/SIZ=ALL/GRAND disk:[000000]user.DIR
Grand total of 1 directory, 1 file, ?/C blocks.
$ SHOW QUOTA
  User  has D blocks used, ? available,
  of ? authorized and permitted overdraft of ? blocks on 

If A+B+1+C=D, then the disk-quota is correct (minor differences can
occur due to multiple header files).

To correct problems use:

$ MCR DISKQUOTA
DISKQ> USE disk
DISKQ> REBUILD
DISKQ> EXIT