Hi,

>>I have Linux, so the typical TCP limitation of Windows XP Sp2 is not
>>the issue.
>>I think is a problem with the dameon that handle Classic Firebird
>>proccess. I have 60 users running simultaneus. the Nr 61 can`t log on.
>>I will seek for Inetd issues in this forum
> The limit of 60 concurrent connections is not new. And, it's not a
> Firebird problem. Look in the xinetd/inetd configuration, the limit of
> server instances might be set to 60, and if it is, increase it. If
> I'm not mistaken, that setting can be set just for Firebird.

True, look here, should point you to the right direction:
http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/ref-guide/s1-tcpwrappers-xinetd-config.html

regards,
Michael