double check that you do not have 2 default.xbes on your harddrive. files should look a little like this:
(the dlc)
e:/tdata/55530005/$c
e:/tdata/55530005/$c/5553000500000001/{files such as briefings and character, ect, should be in here}
(the patch)
e:/tdata/55530005/$u
e:/tdata/55530005/$u/{shell, contentmeta, and stonewallxboxdownloader should be in here, check to see if you have a default.xbe in here. with the patched version there shouldnt be, because the patched version that would be in here is the one that you are overwriting your original with.}