Disable Visual Mode stripping html or code?

[Notspot]

This has me stumped, I need to disable the way the visual editor strips code in wordpress.

To explain, I have a wordpress site where multiple people will be working on the pages in visual mode. The problem is if I add html or code in the html editor all is fine and dandy until someone switches the view to, or edits the page in, visual mode - it auto strips all of the html or parts of my custom shortcodes I've added.

Anyone know how to stop visual mode doing this? This seems like a huge wordpress bug that you can't disable this 'clean up' mode and doing a google search just brings up more disgruntled people but no solutions.