>I have a stored procedure which returns the rows
> using ORDER BY StringField ASC, IDField DESC...
>
> On my machine, it works as expected. However on customer's machine
> StringFields are slighly out of order. For example, it first returns
> Bxxxxxx, then few Cxxx rows, then again Bxxxxx...
>
> What could cause this?

Perhaps leading spaces in data ?

> Does Regional Settings affects this?

No.

> Any FireBird settings in config files?

DoNotSortCsBetweenBs=True

Ivan