Corrupt/missing RPM's - how to repair ?

Trying to PXE-boot/install systems, I hit a virtual brick wall due to a missing or corrupt RPM Lacking any clue, I deleted all references to the offending package from my cobbler-server, resync-ed and I am now running a cobbler reposync in the hopes that the offender will get replaced. Did I do something horribly wrong or what ? “Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us.” Bill Waterson (Calvin & Hobbes)