oh i had the twitter problem so i did
gconftool --recursive-unset /system/http_proxy
gconftool --recursive-unset /system/proxy
gconftool --recursive-unset /system/osso
but didn't do anything....
yes i tried remove,reboot and add,it still disappear after reboot
today i just did a reset/clear device,problem was still there even with remove,reboot,add

so i went ahead and started nsu,told me i was already up to latest so i just click reinstall and what do you know everything works well like before. no problem so far. I did a bunch of reboot in case i was dreaming, my accounts logins are still remembered after reboot so cool.

I was surprised my music,rss feeds,and stuff on mass storage were still there. i though it would have been erased like the clear device option although it did erased the apps.

conclusion:so yea the problem isn't in the mmc/mass storage stuff

EDIT: after a few hours the ''bug'' reappeared...
i tried something, i only removed the nokia account and after rebooting it remembered my nokia username,maybe its suppose to idk.
also after rebooting i went to the feeds setting and only the facebook feed was on,the twitter feed was off saying the account wasn't setup.so i had to enter the twiter username and pw again.