It's due to the IE issue where a largely fictitious date would not be valid; as a "fix" the cookie date is set as 7 days (ie the cookie will be invalid after this date). Myself I think a month would have been a better value.
You can change this, but it wouldn't be supported and you'd have to edit coding to be a different value.
Not sure what you are referring to here about 7. I checked the code, and the cookie is set as time() + COOKIE_LIFETIME, which is set in config.inc.php. It is set by default to a very large number.
Some of my IE users have been having issues too. Should I change the value of COOKIE_LIFETIME? And if so, what its the greatest possible value that will keep IE happy?
