I had an issue that turned out to be a known issue on ubunutu. Trying to launch xlsx or docx or pptx files wouldn't work while ppt, xls, and doc files worked just fine. I saw that the association was there but when you double-clicked on the file, nothing happened.
Turns out this is a problem with the binfmt module that thinks these files are jar files and trying to pass them to java. After trying to do this manually by invoking the script directly I finally saw the error message:
"invalid file (bad magic number): Exec format error"
So after lots of searching I saw that there was an outstanding ticket:
http://www.codeweavers.com/support/tickets/browse/?ticket_id=793030;id=241;tscurPos=200
Being on Fedora 15 the workaround didnt work because there is no such update-binfmt command. I found that there was a service a startup that registered the jar association and that stopping this service got the office files to start working correctly.
To stop the service: systemctl stop jexec.service
To disable the service: systemctl disable jexec.service
Just thought I'd pass this along to those having similar issues on Fedora 15. Might want to update the FAQ page to include this for fedora users.
http://www.codeweavers.com/support/wiki/linux/faq/cxofficejavaassociation