Modifying Keybindgs Anomoly

[Bill]

Given the followng lines from .emacs:

(global-set-key "\C-f" 'delete-selection-mode)

;;(global-set-key "\C-f" 'isearch-forward) 

Note that the second entry use to work fine, but is quoted out, so
non-operating. However, even after reinitiating .emacs the second
entry continues to activate when C-f is entered.

I must be missing something.

bj