For most of the past week I have been having to log into the forum every time I visit. As one who browses here when I get a few free moments from time to time, that makes participating here a fair bit more troublesome.
Nothing has overtly changed on my end - I'm still running the same OS (Windows 7) and browser (IE10). I wouldn't bet a Windows Update didn't cause this, though.
Okay, I appear to have solved it by clearing all cookies and temporary files. But I've only been able to test it so far by closing the browser then immediately opening it to the forums site again. We'll see if it works over longer periods.