Backspace doesn't work in gvim 7.2 64-bit for Windows?

I just installed the 64-bit zipped version for Windows of gvim on my new machine at work, and I changed some settings to make it compatible with Visual Studio 2010.

Now the backspace key doesn't work for some reason.

Here's my .vimrc file:

set nowrap
set ruler
set encoding=utf-8
set fileencoding=utf-8
set ff=dos

It's only a minor annoyance (the delete key works), but I was just wondering if anybody knew.