Recently, I also experienced weird hang-on-close problem.

- I installed FB1.0 (Win2000)
- scanned disk to ensure there is only one gds32
- created empty database (with sweep interval 0)
- imported few thousands rows (via app. using API)
(all this previously done countless times without any problems)

- when playing with apps accessing the db,
all clients hung during disconnecting the db.

* restarting FB did not help
* the customer (of course such things only happens on customer sites) said that
there was previously installed IB6 on the server,
and Windows was not rebooted since uninstalling it.
* when we reinstalled FB, the hang-problem disappeared.
(Although we had to run FB as application; installing FB and running it as service
was possible only after Windows reboot)

*** interesting thing is that FB (before reinstalling it) did not accept local connections
(i.e. d\db.gdb), while localhost:d\db.gdb worked (except hanging on close).

(Normally I always use tcp/ip; the reason I noticed problems with local connections
was that GSEC did not work.)

====
And do you remember scandal with "politically correct" backdoor account
two years ago ? I noticed it in source code _months_ before it was
published, but I _idiot_ tried it only with local db path, which
did not work (remote access is required), and I wrongly concluded
it is just some internal hack, or placeholder, or something like that.
Since then I better test things with all possible protocols,
even if I use tcp/ip exclusively at customers.


Ivan
http://www.volny.cz/iprenosil/interbase