"Disable" the Browser's Back Button

While there is no way to specifically disable the back button from within the browser, you can shortcut the navigation to another page. The trick is to catch the onbeforeunload event of the window:

 
<script language="VBScript">
dim curPage
dim canNavigate
canNavigate=false
curPage=document.location

function window_onbeforeunload()
	if not canNavigate then
		window.navigate curPage
	end if
	canNavigate=true
end function
</script>

Whenever anyone attempts to leave the page, the browser will nudge the user back. You can disable this functionality in code by setting the global variable canNavigate to true.