problems moving

i have just installed wordpress under a directory ‘wordpress’. and its working perfectly fine. now i want to move it to another directory ‘blog’. but after changing it under the options, my wordpress doesnt work anymore.
what i meant by not working, is that the blog doesnt show up. and i cant logout of wordpress. only way is to delete the cookies. and if i do so, i cant log back in. and i have to reinstall everything.