This problem is happening with my Windows 2003 server running Firebird 2.1, too.
One important issue to mention is that this Windows 2003 server machine is running as a workstation, not in server mode.
The fbserver.exe is running as a service. This machine is accessed by more than 100 users that connect to the database.
I wonder if this situation can possibly affect the number of concurrent connections, I mean, is there any difference between running windows 2003 server on server mode and running on workstation mode? the number of concurrent connections is different from both modes?
Any ideas?

Many thanks,

Rogério

--- In firebird-support@yahoogroups.com, "Andre Pietzner" <ap@...> wrote:
>
> >>> About "crash at 63 connections". I'm almost sure it is
> >>> a) not a crash
> >>> b) not a Firebird issue
> >>>
> >>> I saw such limitaion (SS can't handle more than 63 connections
> >>via TCP\IP) at
> >>> computer where ESET NOD32 antivirus installed. Modern antivirus and
> >>firewall
> >>> software often embedd itself into TCP\IP stack and, unfortunately,
> >>often have its
> >>> own bugs. In this case, i think, they used WaitForMultiplyObjects on
> >>user process's
> >>> sockets list to intercept its activity. This introduced limitation
> >>for no more than 64
> >>> active sockets per process, and it looks as user process fault.
> >>>
> >>> Regards,
> >>> Vlad
> >>>
> >>
> >> Thanks Vlad for your explanation. I will try to remove the anti-virus
> >> and firewall software (if any) and will post the result soonest
> >> possible. Thanks again.
> >>
> >
> >Bad news guys! I have removed the anti-virus (AVG Free Edition) and
> >turn off Windows Firewall, but my problem still unsolved. I even
> >upgraded the RAM to 512 MB.
> >
> >Any other ideas?
> >
>
> We have reinstall the Server at that time. It solved the Problem.
> Im sure the Eset NOD32 causing the problem in my case.
> Deinstall the AV was not enough to correct the problem.
>
> best regards,
> André
>