Use a dedicated stable linux box with a UPS system.
Use Firebird 1.5.2 classic server or higher :)
Use a journaling file system, ext3, reiserfs or xfs.
Have forced writes on and I'm sure nothing will corrupt your
database.

But in any case, make daily backups and restore them on an other
machine once a month in order to see if they can restore.

For years (till 97), I'm running machines with interbase and
firebird. The main problem was related with power. When the server
shuts down suddenly because of a power failure the database file may
get corrupted. This problem dissapeared then I started using xfs or
ext3 file systems. On one specific site, there was a chronic UPS
problem and the UPS was shutting itself down many times a day while
there were many clients connected. As they restarted the server every
time I was stressed but nothing went wrong. I am impressed about
this. The system was a linux box(xfs) with firebird 1.0.796.

Don't get this as an advertisement, and I don't have any relation
with those manufactures but I'm mainly using asus boards, kingston
memory modules, thermaltake power supplies, intel cpus (doesn't
matter if it's a celeron)

AMD is ok too, there was some thermal issues with it, i don't know if
there still is, and it had risks for the "setup and forget"
configurations.

I have 17 sites running firebird in other cities and I've never
visited any of them for 2 years. If you make a good environment for
your server, you won't have any problems.

Regards