Wouldn't have to VB, could be C++ et al since the control's an ActiveX, and the same principle applies to all OS that package commonly used components/objects/etc. I was using VB as an example. Could even be done in Java, although not easily.. Alternatively, modify a Firefox version, it's opensource and multiplatform ( maybe write once compile anywhere? no idea ). Intranet implies internal, and companies often control the software on their employees machines.

The popup window method will only work if the browser allows popups, and there's nothing to stop a user re-enabling the toolbar on a popup, or accessing the page without following a path that invokes the popup (i.e direct URL ) still, it's probably a better solution than writing a new browser frontend just to disable 'back'..

I still can't imagine a good reason to disable back. What's the ultimate intention? There will be other means to achieve the same aims ( unless those aims are ultimately to disable back ) without disabling back. That's not to say that those means wouldn't always require any replanning or large modifications; which is why it's a good idea to recognise 'back's' ( and equally 'refresh's' ) existance early on.