go to ~/Library/Receipts folder
look for "MacOSXUpdateCombo10.x.x.pkg" or whatever corresponds to last update you downloaded.
move it out of that folder, close the folder.
Try running the combo installer again.
If that doesn't help, then put the file you moved back into the Receipts folder.
Disk Warrior deals with corrupt directory issues. There could be some other issue with your drive that might warrant full backup, wipe, and restore.