I did four tests on two different platforms:
Test with the VM running Bitnami Alfresco Stack version 4.2e (stable release) + SPP Amp 4.2e
Test with Windows 2003 running Community Edition of Alfresco 4.2e (stable release) + SPP default install
Test with Windows 2008 running Community Edition of Alfresco 4.2e (stable release) + SPP default install
Test with Windows 2008 running Community Edition of Alfresco 4.3a (nightly build) + SPP default install
The same behiavior with Sharepoint Protocol was experienced with all solutions running version 4.2e and with two versions of Office (2007 and 2010)
My last test with a beta release of Alfresco worked directly with the same settings and with Office 2010 + SPP.
I didn't upgrade your stack but by going standalone install of the CE I wanted to confirm the problem was with Alfresco and not with Bitnami.
I am sure you'll wait for the RTW/stable release of Alfresco, wasn't sure if you had roadmap access and knew that the stable release of next Alfresco versson is due in one month, one year or even not scheduled...
FYI, I have fixed almost my issues with this 4.3a version but the outbound emails isn't working (javaxmail pbm).
Will again do some tests to see if it is my settings, a bug or something else not working but hopefully I'll end with a working Alfresco/Bitnami community edition ready for professional tests (emails, CIFS, FTP, SPP) ;o)