I dont't compare firebird to ms sql, and I surley don't give up.
If the database isnt't able to handle such problems one has to invent a workaround. It's obviously a bug that -although the docu says that read committed DOES read only committed records- it doesn't and exits by throwing an exception on an uncommitted record without reading the next committed ones..unique behaviour..

--- In firebird-support@yahoogroups.com, Dimitry Sibiryakov <sd@...> wrote:
>
> > ah..so "SELECT...WITH LOCK"..
>
> Won't work this way either. Give up. You cannot get behavior similar
> to MS SQL.
>
> SY, SD.
>