Unfortunately, I don't believe that you can easily suppress the dialog box, but I may have another solution for you.
Instead of searching for the "No records found for processing" string with Monarch, you could use the DOS FIND command. When you run it with the /c option, you get a count of lines containing your search string, like: [font="courier"] -
MYFILE.TXT: 0[/font][/quote]where zero is found count.
You could redirect the output of the FIND command from the screen to a disk file, then read that file to extract your value. Because the colon character is an illegal character for file names, you know that it will only appear before your value.
Now based on that value, decide how to handle the Monarch processing.
Just an idea. Some bright guy (like Nick ) is bound to come up with something else.