screen screws up my emacs F# key bindings

[Rusty Shackleford]

My .emacs has a bunch of lines like 

    ;;my favorite function key mappings
    (global-set-key [f1] 'find-file)
    (global-set-key [f2] 'save-buffer)
    (global-set-key [f3] 'shell)

Before I start screen, I can run emacs in a terminal window and these
work fine.  Then after I start screen, these just cause "~" characters
to print.

Is there some way to fix this?  Please, no jokes about how the fix is to
switch to vim ;)

TIA