Wirelessly posted (7100t (T-Mobile UK): BlackBerry7100/4.0.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 UP.Link/5.1.1.3)
Error 404 is a server-side error generally. It means exactly what it means on the tin, the server can't find the page you requested, and there's no browser setting you can adjust to fix this. It could be that the pages are loading too slowly on your BB and timing out perhaps. It's more likely that the BB browser can't properly handle the non-WAP/WML page you're throwing at it (could have been designed for IE only), and the server just gives up. Or alternately your webmail server could be screwed
.
In short, unless your webmail has a WAP specific version, the best way to get email on the BB is to pay for it. Either with your network provider or sign up to one of the third-party BES sites listed on this forum. Not an ideal solution if money's tight, but it's the best.