>> > Could someone please point out some possible causes, or what else to
>> > look at?
>> >
>> > Or if someone could fix it in Firebird... :-)
>>
>> Does you tried latest snapshots of 2.0.4 or 2.1 ?
>>
>> Regards,
>> Vlad
>>
>
> Not yet, but we'll devote resources in the coming days to test it with
> 2.0.4.
>
> But since the only relevant bug fixed in 2.0.4 seems to be CORE-1199,
> my question is: Can CORE-1199 can lead to database corruptions? The
> call stack containing BTR_insert suggests it to me.

I'm doubt it can lead to "page NNN is of wrong type (expected 7, found 5)" error.
Make sure your 20% unlucky users really used 2.0.3 and not 2.0.1 (look at
CORE-1300 which was fixed in 2.0.2).

As for 2% of checksum errors - if host application crushed embedded engine
have no chance to correctly flush its cache buffers.

> Testing it with 2.0.1 is currently out of question, as it would
> require more extensive changes in our app.

Does you mean 2.1 (not 2.0.1) ? And what kind of "extensive changes in your app"
it enforced ? Just a question ;)

Regards,
Vlad