Hi Guys ... I'm going to be running a series of updates early tomorrow morning (between 2:00 - 5:00am) that should resolve this issue. This three-hour window is when traffic to the site is at its lowest, so there should be a minimum amount of disruption.
Here's a brief description of what we found ... About 10 days ago we started to run all forum pages from our secure server (i.e. all pages loading with an HTTPS url). After I configured this we discovered a bug in the ad server software that disabled all our advertiser's banners. I disabled the secure server temporarily while I diagnosed this and brought the banners back online, but not before some of your browsers cached the secure pages. Each time you visited an HTTP page, your browser was expecting a secure page and then would log you out. The update to the ad server software should fix this and allow us to run all pages on the secure server while displaying the banners and not have these annoying logout issues.
I'll update you once I've installed the updates and tested.
Cheers,
Chris