Recently there were reports that the WiX toolset was breaking unit test projects in Visual Studio 2008. This was surprised us because we thought unit test projects were working fine when we shipped. Well, it turns out this time the bug wasn't in the WiX toolset.
If I'm understanding this correctly (I'm not a Votive expert), it appears that Visual Studio 2008 Service Pack 1 introduced a bug that caused the "Create Unit Test" wizard to show up blank when the WiX toolset was installed. The root issue seems Visual Studio mishandling projects that do not implement unit test information. The WiX toolset is such a project.
Fortunately, Microsoft provided a hotfix for the problem. The hotfix's KB article even mentions the WiX toolset. I have verified with three people who reported the issue that the hotfix does seem to address the problem.