Over the past few months I ran into the same issue with DotNetNuke 6 websites quite a few times: “I can’t login on my DotNetNuke 6 website with Internet Explorer 10!”
And because Windows 8 ships with Internet Explorer 10 (IE10), and since DotNetNuke 6 websites will not all be upgraded to 7 anytime soon, chances are this issue will become increasingly annoying.