mrtg (PT 7.0 on RH 7.0 system) says: libpng error: Application must be recompiled; version 1.0.6 was incompatible mrtg-2.8.12-7 libpng-1.0.8-1
This was already fixed in an errata. Please see http://www.redhat.com/support/errata/powertools/RHBA-2000-069-02.html . *** This bug has been marked as a duplicate of 17135 ***