Possible Syware - No SystemRoot variable

Had a user the other day who suddenly wasn't getting and drives mapped when he logged onto his computer. When attempting to troubleshoot the problem and jumped onto the command line and typed the usual ping which came back with:

'ping' is not recognized as an internal or external command,operable program or batch file!

This was a bit of a shock as ping is certainly a well known windows app. After ensuring ping did still exist on the user's pc in the correct location, i then (after a bit of a think) tried this:

echo %path% - came back with the correct entries

echo %systemroot% - came back with nothing!

True enough, after navigating to the system environmental variables the systemroot variable was not there - after adding it again all was fixed.

This seemed to be due to spyware as, after a run of CounterSpy, many bits of spyware were removed and has been fine ever since.