A lot of my members having problem logging in 2.2.0 RC 2.

Once they have logged in and refresh the page - sometime it logged them out automaticlly.

However, I have disabled stronghold and this did not fix the problem.

I told them to clear the cookies.. but sometime didnt fix the problem. It is very annoying to tell every members to clear their cookies.

Using IE, it is necessary to set your cookie domain in the cookie settings in the ACP.
RC3 we've added code to try to prevent not having a cookie domain being set from becoming an issue.