You can't properly disable the back button...no browser's allow you to do that. Opening a new window with no toolbar is one possibility, but you can often use ALT+LEFTARROW to go back. You can't open a new window and automatically close the old one (unless the old one was created using javasctipt). Tis some security thingy built into javascript.

Best bet is to either use a redirecting page so when the user clicks back they get the redirect page that sends them forward again. Problem with this is that IE & Netscape give you the option to jump back more than one page at a time (bypassing your redirect page).

The other option is to have all your pages generated at runtime (with asp or something similar) and give each page a unique id number...if a user requests a page with an id number that has already been used then deny the request. This would also disable the refresh button too. Problem with this: when IE is in "Offline Browsing" mode it will happily go back to a server generated script page from its cache...without re-requesting it.

Conclusion: it can't be done...not completely...there's always a way to go back. Sorry.