>>As you said the issue occurs at only one customer i guess his HW or
>>SW have something which make FB work badly. As you said you changes
>>different VMs and OSes, i guess this may be HW or host OS related.
>
> It is not HW nor SW. The only special thing about this customer is load.
>
> The ~60 users using the system are really hammering it. It is the most
> active customer by far.

Ok, not HW. What they did with security2.fdb to corrupt it ?

Regards,
Vlad