Vista-Ultimate: Can't open one sub-dir in encrypted archive

Hi,
I encrypted a dir using "right-click/add to new encrypted archive" option
in vista. All sub-dirs could be locked and unlocked fine (from windows
explorer interface). But, for the past few days one sub-dir gives an err
message as follows: (I have Vaio with a fingerprint reader)

"0xe7580003: Archive file was not opened. Authentication failed."

remember that all other subdir's in this archive open fine except for this
one (and only recently), so some kind of corruption seems to have taken place
and I don't how or why.

My question is this: is there a way to recover this encrypted subdir? I
have tried to delete, unlock, etc. but nothing seems to work.

-thx.