1201: unable to find overlay file <filename> in current PATH
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 This message indicates that either too many files are open or that the
 external overlay file <filename>, specified and created at link time, can no
 longer be found in the current directory or the current PATH.

 Ensure that the overlay file is in the current directory, the directory
 containing the .EXE file, or in a directory in the DOS PATH. If so then try
 marking the .EXE and overlay file(s) read-only

 Note: The Blinker errors 1201 through 1204 can occasionally result from the
 effects of a virus, so if the above measures do not help then perform an
 extensive check for viruses and take the necessary measures for removal.