Getting bumped to the home page

I was curious if anyone else was having this issue. I dont want to say problem, because, well it's not much of a problem. But sometimes I'll leave myself logged onto ATS for the entire day while I'm at work, or away for a day or two, and when I come back and click on the 'todays posts' link it will kick me out to the ATS front page. it usually happens about once or twice a day. Like I said, it's not really a problem but am mostly curious if anyone else has this happen to them?

I'm dual booting on a XP/with Opera for browser, as well as a RH 9 install with Opera on that as well. so I'm guessing it's something to do with Opera???????