vi - vim backspace leaves ^?

Question

In Vim, when I hit the backspace key in the insert mode, it leaves ^? character and does not delete the character it is suppose to delete.

I have the following in my .vimrc

syntax on
set number
set expandtab
set incsearch
set nocompatible
set backspace=indent,eol,start
fixdel

This happens in the command mode too. When I wrongly type W instead of w to save, I press backspace key and it gives me the following:

:W^?

Any idea on whats wrong and how to fix it?!

UPDATE: before posting this question to SO, I have done a basic google search and tried all the suggestion from the first page of search result but unsuccessful.

@strcat I'm using vim version 7.0.237, KDE console 1.6.4, Linux 2.6.18 x86_64 machine.

@graywh w.r.t cat -v, for delete, I get ^[[3~ and for backspace, I get ^?.

The output of stty -a is as follows

speed 38400 baud; rows 38; columns 194; line = 0;
intr = ^C; quit = ^; erase = ^H; kill = ^U; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V; flush = ^O;
min = 1; time = 0;
-parenb -parodd cs8 -hupcl -cstopb cread -clocal -crtscts -cdtrdsr
-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr icrnl -ixon -ixoff -iuclc -ixany -imaxbel iutf8
opost -olcuc -ocrnl onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
isig icanon iexten echo echoe echok -echonl -noflsh -xcase -tostop -echoprt echoctl echoke

Answer 1

^? is the delete character; the backspace character is ^H. Only one of these is recognized by your terminal as "erase", and this is determined by the terminal settings, stty. (bash and other shells understand this as a problem and do special things to recognize both)

If your terminal emulator (ssh, putty, xterm, whatever) disagrees with your terminal settings, then you see this behavior. Usually it's right by default, but very often people will put stty commands in their .bashrc which breaks things.

You probably have something like stty erase ^H in your bashrc. If you do, get rid of it, or change your terminal settings to have backspace send ^H instead of DEL (^?)

You can also fix this with vim mappings, but that's ignoring the basic problem.