The quick answer.  Rename coiwrite.exe to coiwrite.sav
If you then decide to run COI in the future rename coiwrite.sav back to coiwrite.exe

The long answer.
16 bit DOS programs will only write files with 8 character file names.  To allow the full 18 character file names in COI NPED writes two files coifleid.txt and coidata.txt in the NPED directory.  It then executes the program coiwrite.exe to rewrite the coidata.txt as a ?.csv file in the coipath.txt directory.  If it attempts to write and coiwrite is not found the program continues to run leaving coifleid.txt and coidata.txt to be overwritten the next time the [build coi file] is requested from the bird or pair [ DETAILS F2 ] list.