I can open in Calc ver 4.1.5.3 did they decide to drop the compatibility in the latest Fresh version? Now I get Incorrect file version error. or it tries to import the encrypted file as txt.
Please write a bug report about it. I can confirm that 4.2.2.1 does not work with password protected docx, while 4.1.3.2 works just fine. And don’t forget to post the link to bug report back here.
Already reported by another as a Bug https://bugs.freedesktop.org/show_bug.cgi?id=76222
I guess we watch and wait.
(Friday Mar 28 09:19 2014)
I have tested the latest DEV build http://dev-builds.libreoffice.org/daily/libreoffice-4-2/ and confirm that I can now open the protected xlsx file. Hoorah!
Forrest
Yaay! That wasn’t so long at all 
The bugfix will be available in LibreOffice 4.2.4.