I found that it seemed to have kept some old config going from stock > DD-WRT > stock, at least it was asking for a password as well. I did a hard factory reset after to completely clear it.
Found stock to be crappy, so much so I went back to DD-WRT.
To which version have you returned? I've found that just 1.20 is usable over longer period of time - other versions (even latest 1.30) seems to work weirdly and requires rebooting...
(thought to go to 1.20 - I've to always go first to 1.04(unencrypted) and on top of this I can upgrade to 1.20.
BTW - openwrt starts to work with 882 too - but it's has quite some issues as well...