I've run into a weird problem in ArcCatalog where I've got a network dataset (that I've built fine before) that I've gone into and switched my connectivity groups around. When I hit "OK" and then right click on "Build", it goes through all the motions, looks like it finishes okay (i.e., it closes on its own and does not come up saying "build completed, but with errors"), but when I click on it and look at "General (tab) -> Build Status" it still says "not built", and I can keep trying to build it without it ever bringing up the "The network dataset has already built" message that I normally get if I try to build a dataset twice.
Has anyone run into this before and knows what causes it? The only thing I've noticed is that it seems to "complete" the build faster than it should.
The build log files are kept in the temp folder. So go to your %TEMP% folder in explorer and see the contents of the BUILD.TXT and/or BUILDERRORS.TXT to see what was done. Perhaps that will give a clue to why the network is not building. Another thing you can try to do is create a new file gdb, feature dataset and then copy the network dataset to it and re-build and that may provide some additional information as well.