Ancestor table can get corrupted (sometimes Page.getAncestors() can return duplicates).

This can cause issues when WebDAV's strict path checking functionality is enabled (WBDV-204), rendering the Office Connector plugin useless as a result: http://confluence.atlassian.com/display/CONFKB/The+Internet+Address+Is+Not+Valid+Error+Message+due+to+Corrupt+Ancestor+Table.

We are still investigating this issue and are looking for sample backup to allow us hasten the fix.

If you are willing to participate, please let us know: http://support.atlassian.com (an anonymized backup should suffice).