Hi,
That error is usually returned when the specific file you are trying to use can't be found. Off the top of my head I'd look at two possibilities - first that the files aren't there (Unlikely), but check in system32 and see if you can find them - ping.exe, tracert.exe and net.exe. Next look at the PATH variable on your machine. You probably know this anyway but this system variable (which can be seen by running SET PATH in a command window) is the list of directories that windows will look in when the file that is being called is not in the local directory. A quick test to see if this is the problem is to open a command prompt, CD down to system32, and try a ping from there. If that is the problem, then you can modify the path from my computer \ properties, compare it to a known good machine and alter as required. If neither of these proves to be the issue, then reject this message (to let me know) and I'll give it some more thought..... Hope it goes ok : )