I am not aware of a built-in LabView vi called "DIO Stop.vi" (not in versions 5.0 thru 7.1)
It must have been implemented by the programmer.
Open the LLB manually and see if the file exists. If it exists open it, then open the main vi
If you do not find it or if it got corrupted, use the version 6 of the LLB assuming it is aviilble, open the vi, and save it to a new destination.