> We have Firebird 1.5.2 SuperServer and our client application creates
> new threads for each database connection. When two connection requests
> occur simultaneously in our multi-threaded environment, a call to
> isc_attach_database is made, and then another call to
> isc_attach_database occurs before the first call has returned, and
> neither call returns.

It seems you are using local connection. You have to use network connection, e.g.

"localhost:d:\mydb.fdb"

Ivan