problem upgrading from 2.0 RC1-1 to 2.0 RC1.2

[ɔɔɔɔɔɔuɥoɾ]

Must be the database, its the only thing your preserving try creating a complete fresh forum with new database too, see if problem still exists

[hijinx]

okay, i can try that on monday.

if that is the problem, what in the database would result in a 404? the database shoudn't be directing traffic. It shouldn't be determining what links go where, as far as I know... but then again, I don't know much. 

[ɔɔɔɔɔɔuɥoɾ]

Well,
Neither one of use know what is actually is yet, but, from the thread, I see that:

1. You have changed Host // Not host

2. You have installed fresh SMF and imported database  // not script in PHP files.

3. You have checked Permissions on all files //not permissions.

4. Whats left  // Database/MySQL server problem - more your database though

As for database redirecting traffic, no I don't see how, but PHP and MySQL is pretty powerful stuff, and it could be something simple like a redirect been echoed from the database, and yes, How they hell would that get in the database and echoed on those redirecting areas, its a mystery.