Trouble logging on to POTN in new install of IE 11

I had to re install Win 7 with IE 11, and when I went to POTN, a dropdown said it could not find a "Guest Cookie" and would not let me log in. I tried to lower the Privacy setting to the lowest level in Internet Options, without success. I included POTN in the Compatibility box, still no luck. Aldo tried deleting History and other cookies, no dice.

I'm logging on now with Firefox, but would rather use IE. Any suggestions would be greatly appreciated.

Figured it out, with the help of Pro Support at Dell. This is a T7910 Precision Workstation which I just changed the mother board on. After trying everything I could think of, compatibility mode, privacy settings, I called Dell where I was smart enough to have bought a 24/7 support contract when I bought the new computer.

After checking a few things, the tech asked if the time was correct on my computer. The clock? I thought, let me check. The gadget clock said 9:50, which was correct, but the clock in the Taskbar said 9:50 AM! I changed it back to PM. The tech said check the BIOS. Not only did was the BIOS time an hour slow, but the date was the 25th rather than the 24th.

I corrected the BIOS, rebooted...and logged right into POTN in IE 11.

Umbelievable. But the tech told me the story of sending out a new motherboard to another client, and the new board would not work at all. After checking some things, they found that the time was incorrect in the BIOS. Correcting it got the motherboard working right away. He said that my being able to log into some sites but not others was a classic example of the problem.

Thank goodness for Dell Tech Support. These guys and women are based in Texas, and there has never been a problem that they couldn't solve for me over the past 15 years.

Agreed. My experience with Dell support was first rate. Back when I had several Dell servers in my shop, they handled everything.
If they couldn't fix the problem with remote access, they had a technician at my door in half a day.