No syntax highlighting in GVIM on Windows with _vimrc

The gvim program alone does not have syntax highlighting enabled by default. Syntax highlighting is only enabled by explicitly enabling it with a command such as :syntax on. So the only way to have syntax enabled is to enable it yourself at the Vim command line or to have such a command in a configuration file that's read on startup.

Vim is typically installed on Windows with a standard set of configuration commands in C:\Program Files\Vim\_vimrc. That standard set includes syntax on. Without any other configuration files, gvim will read that file on startup and you will have syntax highlighting.

In :help _vimrc it says, "Four places are searched for initializations. The first that exists is used, the others are ignored." The list of user vimrc files includes $HOME/_vimrc followed by $VIM/_vimrc. On your system, $VIM is C:\Program Files\Vim.

So, when you use a C:\Documents and Settings\myUsername\_vimrc file, gvim reads that file and skips C:\Program Files\Vim\_vimrc. If your _vimrc does not contain syntax on you will not get syntax highlighting.

If your are going to use your own _vimrc, then make sure you copy into it from C:\Program Files\Vim\_vimrc any of those configuration commands you need, including syntax on.