Ok, let's say we think your ISP may be running a transparent caching web proxy, one way to find out is to try some on-line test, like this one:
http://www.all-nettools.com/toolbox,net
(scroll down and click the CHECK! button under the "Proxy test" section).
Does it say "Proxy server detected"?
or try this one:
http://www.broadband-help.com/cm_diagnose.asp?init=1
Under "Proxy Information" at the bottom of the screen, does it say "Proxied HTTP? Yes"?
Can you give these tests a try and let us know if they detect a proxy?
(Edit Update...)
If you find you are using a proxy, that proxy will also be a suspect for the problems you are having. We can try a different proxy in an experiment to see if that supports that hypothesis :)
The thing about transparent proxies, is that they generally work by "grabbing" all your network traffic that goes to some other site's port 80. Port 80 is the standard www port used by web servers. They could also grab traffic on other ports, but knowing if they do that is a little more difficult.
Anyway, this is to say, if we try using a proxy that does not use port 80, maybe we'll see a difference in behavior, and that would indicate a problem in your ISPs transparent proxy.
To find another proxy to use, you can search on google for "(free|open) proxy servers", or something like that. Here's one site I found:
proxyforest.com. It's in Japanese, but the list of proxies it has is in English.
Find a proxy on the list that does not use port 80 (warning, some will not work, so this could require some experimentation). For example, I just tried 201.242.177.232:8080 (that's given as IP : Port), and it worked for me. Now edit your browser's proxy information preferences to set the proxy IP to 201.242.177.232 and the port to 8080. If that doesn't work, just undo that information and try another one.
Once you've changed your browser to use another proxy, you can go to some site like
ipchicken.com that will tell you your IP address and see
if it has changed. If it has, you were successful in correctly setting up your proxy settings. Now try visiting jdorama.com and see if you see a difference in behavior.
This isn't 100% guaranteed foolproof experiment, but if using a different proxy allows you to access the site, then it does put some heavy suspicion on your ISP's transparent proxy.
P.S. using one of these other proxies is almost always going to slow down your internet browsing, so don't forget to undo the changes you make after you are done.
I hope this information is a little useful to anyone who is having problems accessing the site. I know it may sound complicated, so I guess the best advice is to try your ISP help desk first, but if you feel frustrated by them or a little adventurous, give this method a try. Good luck.