I've been tring to combine 3 steps of check out process into one page, but I got a quite strange problem:

If I choose any one of two shipping methods, and press next to the checkout confirmation page, and then press BACK on the browser. My previous choice was saved successfully. However, if I sign out once and sign in again, do this again (choose any of the shipping method and goto next page, and BACK again), all my choice was gone and have been reset to default.

Has anyone got any ideas?

BTW. in the cofig setting, I've choosen Recreate session to TRUE.

Thank you