Hello, when I apply johnson.all.pairs.sp to certain graphs, R hangs. The R window can still be resized, minimized etc. and the "stop current computation" button can be pressed (though nothing happens). The computation can be interrupted by attempting to close R, then pressing "cancel" when the "save workspace" dialogue opens. However, R then becomes unstable and shuts down without warning. The error also causes R to shut down occassionally. I have this problem with 2 of 35 graphs I am analysing. I can provide an example of a test graph if anyone would be kind enough to test this on their system. System is: Microsoft Windows XP Pro, SP2 Dual Pentium Xeon processors 2Gb Ram Software is: R 2.3.0 RBGL 1.7.10 Many thanks, Dan Bebber Department of Plant Sciences University of Oxford