Hello arcow
I'm using "VIM - Vi IMproved 7.1 (2007 May 12, compiled Jan 8 2009 02:18:41) Included patches: 1-138" and don't experience the behaviour I think you describe.
Which command are you using to start vim and what is it after resolving any aliases and symlinks?
What exactly happens? I run the command vi which resolves to running /usr/bin/vim.gnome (on ubutu 8.04.2) and it doesn't insert any matching parentheses, brackets or braces. It does highlight any existing matching ones -- which is on balance more helpful than tedious.
The fact that nobody has jumped in to answer your question suggests your system is configured unusually. You could disable your vim run customisation (.rc) files by renaming them. Use vim's --version option to get a list of them. If you still have the behaviour with all of them moved aside then the behaviour is configured in the executable
but hopefully not and you can restore the .rc files one at a time until you find the one that's causing the problem then comment half of it out ...
Best
Charles