Don't know if this is much help but i had a very similar problem recently. I could not follow any thread or post/login through my laptop. I could open the first page and no more.I could then advance one more page my clearing cookies every time. Went to the desktop and set the same ticks in boxes in tools>internet options>advanced and all seems ok. Now the bloody PC is playing up and doing the same!
I can only login for one session on the laptop even though I ask it to remember me.
Good luck!!