I have been suffering from this issue for awhile now and can't figure out why this is happening.
I had a LinkSys wireless router and I had trouble connecting to the admin page. It was really slow to load or only loads part of the page. So I thought my router was going bad so I went out to buy a new router. Same thing happens. The internet works just fine though.
My main computer is connected via ethernet cable. If I use another computer to connect to the router admin page, it works just fine.
I am currently using Windows 8 x64. I have Agnitum Outpost Pro 8 and Kasparsky AV 13 installed. I suspect its one or combination of those security programs that is causing the problem but I don't know what to look for.