The fact that you can reach the site via a proxy suggests that your provider may be blocking it. Have you done a trace route to see if your packets can reach the site? If you're not familiar with that, and assuming you're running Windows, do the following:
Open a command prompt. You should get the following:
C:\Windows\system32>
type in "tracert www.adultdvdtalk.com" without the quotation marks, so you have this:
C:\Windows\system32>tracert www.adultdvdtalk.com
Hit Enter and see what happens. What you should get is a message stating:
Tracing route to adultdvdtalk.com [216.55.179.32]
followed by a list of routers (addresses) that pass your traffic on to this site, ending up with this site's IP, as noted above, along with a message that the trace is complete.
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