I am using the latest version of the doxygen 1.3.9,graphviz packages & Fedora Core 1 to generate call graph documentation for my source tree. After generating proper call graphs for a while it stops working and spits out "Generating call Problems running dot. Check your installation! Problems running dot. Check your installation! Problems running dot. Check your installation!" I don't where/what to look for with log or sign of crash. Thanks Raghu.