Calculating world dependencies /
!!! Multiple versions within a single package slot have been
!!! pulled into the dependency graph:

dev-libs/xerces-c:0

  ('installed', '/', 'dev-libs/xerces-c-2.7.0-r1', 'nomerge') pulled in by
    ('installed', '/', 'dev-libs/xalan-c-1.10.0', 'nomerge')

  ('ebuild', '/', 'dev-libs/xerces-c-2.8.0', 'merge') pulled in by
    ('installed', '/', 'app-emulation/virtualbox-1.5.6', 'nomerge')
    ('installed', '/', 'app-misc/strigi-0.5.7', 'nomerge')