Background:
A customer bought a new computer, Win7 64-bit, with a 2 disk RAID configuration. The system was installed by a person who said to me 'I am not a professional, this is more a hobby'.
My task was to transfer the application and data from the current server/workstation (XP) which has run for years, to this new system.

I do the following:
Copy the application folder (applications written in Delphi)
Copy the data folder
Download FB 2.5.1 (32-bit) from firebirdsql.org
Download IB_SQL from IBOjects
Install Firebird (SuperServer, not changing any default settings)
Edit aliases.conf
Perform the simple setup the application requires (specifying the connection string to use)
Start application, which fails to connect (with the error I get when the FB engine is not running or the path is wrong)
The Firewall (AVG ant-virus) is the first suspect, I put port 3050 onto the exclusion list.
Still fails to connect.

Experimenting a bit I find that there is no problem when using the XNET protocol (so FB is running, also checked under services) but none of server:alias, server:c:<path to DB>, and substituting localhost for server, works. Neither does \\server\c\<path to DB>.
I thought maybe there is mistake in the FB alias setup. I connect using IB_SQL and XNET, then copy and paste the path to the alias.conf file.

I edit the hosts file and insert a localhost entry.
I edit the services file and add gds_db 3050/tcp.

Still no connection (other than XNET).
We uninstall AVG and disable the Windows Firewall (was turned on during the AVG uninstall).

No connection.

Using IB_SQL at various points during the foregoing showed exactly the same behavior as the application.

I tried using telnet to check the port but telnet does not exist on this system.

Does anybody have an idea why this system would not allow TCP/IP connections?

Thanks in advance
Peter