> For the second time the backup of our 3G Firebird 1.0.3 database has
> been corrupted.

* Any messages during restore ?
* Any messages in firebird.log file ?
* Have you tried both transportable and non-transportable backup ?
* Have you tried restore "one table at a time" or deactivate indexes during restore ?
* Do you have enough space on disks where database and temporary files reside ?
* Perhaps some viruses or antiviruses can interfere ?
* Somebody (or some application) is trying to connect during restore ?
* Do not you use some tools that directly modify system tables ?

> All tables in the restored database then appear empty
> i.e. result sets from selects are empty and the roles have disappeared.

So not only data but also metadata are missing ???

* Have you tried metadata only backup ? What is the result ?

Ivan