Index: /trunk/src/VBox/Additions/x11/Installer/98vboxadd-xclient
===================================================================
--- /trunk/src/VBox/Additions/x11/Installer/98vboxadd-xclient	(revision 54179)
+++ /trunk/src/VBox/Additions/x11/Installer/98vboxadd-xclient	(revision 54180)
@@ -22,8 +22,11 @@
 done
 
-# This script can also be triggered by a connection over SSH, which is not what
-# we had in mind, so we do not start VBoxClient in that case.  We do not use
-# "exit" here as this script is "source"d, not executed.
-if test -z "${SSH_CONNECTION}"; then
+if test -f /proc/modules && ! grep -q vboxguest /proc/modules 2>/dev/null; then
+   # Do not start if the kernel module is not present.
+   notify-send "VBoxClient: the VirtualBox kernel service is not running.  Exiting."
+elif test -z "${SSH_CONNECTION}"; then
+   # This script can also be triggered by a connection over SSH, which is not
+   # what we had in mind, so we do not start VBoxClient in that case.  We do
+   # not use "exit" here as this script is "source"d, not executed.
   /usr/bin/VBoxClient --clipboard
   /usr/bin/VBoxClient --checkhostversion