Info Node: (efaq)Spontaneous entry into isearch-mode
(efaq)Spontaneous entry into isearch-mode
Why does Emacs spontaneously start displaying "I-search:" and beeping?
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Your terminal (or something between your terminal and the computer)
is sending `C-s' and `C-q' for flow control, and Emacs is receiving
these characters and interpreting them as commands. (The `C-s'
character normally invokes the `isearch-forward' command.) For
possible solutions, see Note:Handling C-s and C-q with flow control.