Some sites are blocked by ISP or other systems so a proxy is required. Not much new about this to add since it's been on many discussions over the years. It's rarely your PC but if it is, it's something like your security choices.
Bob
I'm using Firefox (although problem persists on Internet Explorer) and there is one specific Website I cannot load, unless I use a proxy.
I have tried:
Clearing Cache and Cookies
Using the IP address
Switching to OpenDNS and GoogleDNS
Flushing DNS
Checking Host files
Checking Firewall
Restarting Computer
Checked if the Website is down (it is not)
Is there anything else I haven't tried? I visit this site often so I could use some advice

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic