Problem:
Client application will not see events if NT Service Pack 2 or 3
 was installed.

Solution:
The information in this article applies to:

* InterBase 4.x
* InterBase 5.x

This is caused by a new TCPIP.SYS that modified some Out 
of Band data routines, which InterBase heavily relies on for
 event processing.  The solution is to download the Microsoft
teardrop fix (which includes a new TCPIP.SYS) from

ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/
nt40/hotfixes-postSP3/teardrop2-fix/

NOTE: This fix supercedes the ICMP-fix, the OOB-fix, and the
 Land-fix hotfixes.