I have tried doing this a few times, each attempt has forced me to
completely remove the entire database and start from scratch.

(i'm migrating from the hell that is mysql so bear with me)

heres what I have

create table users (
uid integer not null,
username varchar(32) not null
);

create table info (
uid integer not null,
name integer not null
);

I add an index and a constraint...
alter table users add constraint uid primary key (uid);
create unique index username on users(username);

heres where the problem kicks in:

alter table info add constraint KEY_UID foreign key (uid) references
users(uid) on update cascade on delete cascade;

unsuccessful metadata update
-object USERS is in use

Anyone know how could this be? I have no data in the table users, I
have tried restarting the database server (its built as superserver),
and i've tried to delete/deactivate my constraints I have put in to
try and get rid of the problem.

alter index key_uid inactive;
Statement failed, SQLCODE = -607

unsuccessful metadata update
-MODIFY RDB$INDICESS failed
-action cancelled by trigger (3) to preserve data integrity
-Cannot deactivate primary index

This is very very frusterating, I can't even build a simple db, I
never have seen these sorts of problems even with postgres.