What version are you using? What search options are you using?
Testing with ME 10.03. If I empty the search string field, I just get a message of ‘ "" found 0 time(s)’ or ‘No more occurrences’
I tried with a several different search options, but didn’t encounter this issue.
I am using 10.03. It for one is in the find and replace with both the ‘Search for’ and ‘Replace with’ fields empty, using perl regexp and Global search selected. Then when I select the ‘All’ button the fun starts. The ‘Replace with’ field does not have to be empty though.