Forum OpenACS Development: Re: logged out resets session cookie on every request on IE?
One detail not included there: it had something to do with the domain name the site was running on. If I had the site running on a temporary domain all was fine, but as soon as I switched it to the official domain this problem would appear. And of course, only in IE.
I eventually gave up; I was moving the site from one system to the other, which didn't absolutely have to be done, and I got tired of chasing my tail. So I never tracked it down. It could have been anything, since I was also moving it to a much newer version of Linux and lots of things were upgraded. Though what any of that could have had to do with the domain name, I never did figure out.