Windows 7 - firefox can't access website

Ever since 2 days ago, I haven't be able to get to onemanga while all other website are still perfectly normal.

At first I thought the site was down but siteknocker confirmed the opposite and my friends said it's still up and running for them. In addition, when I switched to IE, it still load the website like normal. If I keep trying to reload the site, I can get through but then got kick out again after around 10-15 minutes or so.

Clearing cache, deleting cookies restarting firefox/windows, reinstaling firefox are equally useless. Anyone know how to fix it?

If re-installing Firefox didnt fix it, it probably isnt Firefox. What firewall, and anti virus are you using? What addons to Firefox? have you launched Firefox in safe mode?

Tried it on safe mode, it's still the same.
Add on:
-Google toolbar
-Java console
-Kaspersky URL advisor
-Realplayer browser record plugin

Antivirus: Kaspersky internet security 9.0.0.736

Firewall: um... the windows 7's default one? How do I know which firewall am I using?

Personally If I were you I would kill the google toolbar and realplayer as I find it bloatware and can be a bit annoying, unless you use it for something.

Is that the only site that you can't get into? It is possible that Kaspersky is blocking it because of malicious content. Just make sure its on the white list of Kaspersky. Also check to make sure that it isn't malicious because if its blocking it, it probably has a good reason to do so.

Couple of things on this page, you may not have tried.

Firefox cannot load websites but other programs can

did u tried in private mode?