ncurses and ls problem - I thought they're colors but it's not!

[Luca Ferrari <fluca1978@infinito.it>]

Hi all,
I'm quite attonished by this problem. I've got two Linux server on two 
different networks, connected thru a vpn tunnel (made by hardware). Until 
yesterday everything was working fine, today there's a strange behaviour. If 
i conenct (telnet,ssh) from server A to B, then I can execute each 
application. If I telnet from B to A I cannot either do ls. I mean, the 
command is parsed, then no output is presented and the cursor remains 
waiting, without presenting the command prompt. After a while I found that 
the problem was related to use of colors in ls, and in fact removing the 
colors (my ls was aliased as ls='ls --color=tty') I was able to do ls and to 
see the normal behaviour. But I'm unable to execute any other program, either 
ncurses based ones, either emacs, either 'env'. 
I've tried to change the TERM variable (that on both hosts is set to xterm), 
trying vt100, but I cannot get the system working.
I've trying to connect to A and B separately from another network, and both 
work. Thus the problem seems to be between A and B, or better between the A 
network and the B network. Of course, nothing changed since yesterday, and 
I'm sure of that!
I've tried to reset routers and vpn appliances, and I've checked that there's 
not a firewall that blocks connections (and in fact all protocols seem to 
work, and speed is good as usual).
Where should I look for?

Luca