Problem: Calling a REXX cmd leads to the error message Program is unreadable.
Hint: This error is generated if a CMD-file called with the CALL statement is locked or deleted by another process. You'll get this error also if the function name for a CALL statement is a directory name or a device name (e.g. call con, see Reserved directory & file names). The above is also true for function calls. (see also REXX programs without an extension and Error: Failure during initialization)