Senbag --
Before you level multiple projects, I would recommend that you close all
projects and then exit Project Professional 2007. When you relaunch the
software, deselect the "Load summary resource assignments" option in the
Login dialog and then click OK. Now you can open each of the projects in
which you have resources overallocated across the projects and level
successfully without "interference" from projects you do not have open.
Although I do not see the Publish operation as "mission critical" to your
leveling operation, it certainly would not hurt. Also, I would recommend
that you using the Resource Usage view for leveling your overallocated
resources, as this will allow you to level overallocated resources either
individually or in groups of your choosing. Hope this helps.