[resolved]problems Accessing Certain Servers

for the last three days I have been unable to access certain sites with my desktop system, and am wondering if there is a simple fix for this

The site's servers are located in the Netherlands, and the Russian federation

I am able to access everywhere else that I have tried

I get a popup window with this in the box

Firefox can't establish a connection to the server at xxxxxxxxxxxxxxxx

* The site could be temporarily unavailable or too busy. Try again in a few

moments.

* If you are unable to load any pages, check your computer's network

connection.

* If your computer or network is protected by a firewall or proxy, make sure

that Firefox is permitted to access the Web.

I am able to access these same sites from another laptop in the house, so it seems to be a problem only with the desktop

.................any ideas would be appreciated, from tech support or even members here