Might be your electrical installation indeed. One night at my grandparents', I turned on my comp, and it caused the whole appartment to go off. The worst was that it wasn't our fuses going off, it was the old security fuse in the service stairs that would shortcut, so we had to wait for it to calm itself before we could have electricity again. My computer had a slight power defect, that combined with the old plug it was in and the old lines and fuse would just shut down the power even before our fuses would trigger.