The operation timed out when attempting to contact ...

We are using gecko (XULRunner 1.8.1.3 and javaxpcom) in our
application to load web pages for given urls. It was all working fine
until we asked it load one particular site. It gave 'The operation
timed out when attempting to contact www.xyz.com' message for that
site. After going through some posts I have increased system tcp/ip
connection max retransmission requests (TcpMaxConnectRetransmissions)
and hence the connection timeout period and tried. It did not make any
difference. So we changed the above setting back to original as it did
not help. Worst part is it now gives the same time out message for any
site that we try, even for ones it worked earlier also. So it became
fully unfunctional now. We can not load any page with it. Did any of
you seen this kind of problem earlier? It will be of great help if you
know the reason for it and a solution and please let me know. Thanks
in advance.