Another problem, here is an example to reproduce this issue:

Text file: 1 line “ABC” x 100,000 times = ABCABCABCABC….
1. Find “ABC”
2. Select “Escape Sequence”
3. Replace with “ABC\n”
Windown 8,1 system will be no response unless force shut down the computer (press the Power button for a few seconds).

If select “Regular Expressions”, it is OK.