is there some overriding reason you don't want to mention the URL? Knowing it might help.
First thing to try though is to open a Command Prompt (Start | Run | type CMD.EXE then click OK or tap the enter/return key)
In the Command Prompt window that opens type the following (substitute the actual domain):
tracert www.siteyoucan'tsee.org (then press the enter/return key)
You should see something similar to the following pop into that window:
Tracing route to www.siteyoucan'tsee.org [2126.96.36.1996]
Let the trace complete to ensure a connection can be made, but the part you are really interested in is the number in brackets (in the made up example above that would be 2188.8.131.526)
Now that the route has been traced, open your browser and type the following into the address:
http://2184.108.40.2066 (click go, press enter or whatever you prefer to try to access the site)
If using the actual IP address allows access to the site, you were either blocking the name through your router or through your HOSTS file and only need to remove the block.
I can not access one (and only one) website (a local service organization I belong to) from my computer. Others in the organization have no trouble getting onto the website. I have an HP Pavilion a1130n desktop with Windows XP, Charter cable internet service, Belkin router with wired connection to my desktop, Comodo firewall. I have disabled the firewall, reset my internet conection, and tried using my laptop to get to the website but no luck.