Konqueror should work fine, as all the other KDE or GNOME applications.
If you didn't do so already, try starting Konqueror on the command line,
in a console window. This will probably tell more about the reason it crashes.

Try creating a new user on the workstation and enable NX access to this new user.
We have had, in the past, some reports about KDE configuration files or UNIX
domain sockets becoming corrupted for reasons independent of NX, for example
if the workstation was shut down uncleanly or if a new KDE session is started
from remote when an existing session was already running from the console. Running
konqueror from a new user should tell us if this is a KDE or a NX problem.