Sounds like I'm crazy, but:
Has anyone ever experienced a firebird installation vanishing from one
day to another from a computer?

Within three weeks it's now the second time that a user's calling me,
telling that my program isn't running any longer.

This program's installed usually on a server together with FB (1.5.5, SS
Win) and executed as a scheduled task via a batch script every day or
every week or so.

As usual the customers claimed they didn't uninstall firebird, but if
you have a look at the machine there's no more service left and in the
firebird program directory just the modified files (like security.fdb,
aliases.conf) and some batch-scripts in the bin-directory (which I use
for backup and adding Admin user) are left, everything else is gone.

Just as a regular de-installation does.

When that happened the first time I was sure the customer did that, but
now that it happened again at another site I start wondering if there's
some tool (antivirus or whatever) out there which might be running the
uninstallation routine.

In both cases the server is set up and usually not used by anyone else
(login) and just left alone.

Luc.