With some web clients (particularly Mac OS 10), mouse tracking does not work well.  The fix is to disable mouse acceleration on the Linux computers:

1. Configure the Linux windowing system to use Gnome (select gnome using the session menu on the login page)
2. Modify “.gconf/desktop/gnome/peripherals/mouse/%gconf.xml” in the user’s home directory
3. Search for “motion_acceleration” and change the float value to 1.0
4. Log out and back into to enable the changes

An alternative fix is to run

xset m 1 1

from the command line, or as part of your startup script.

To run the Avocent java-based console application on Mac OS X:

1. Click on the console button on the web page
2. Save the kvm.cgi file to some location.  Right click the file, select open with "/System/Library/CoreServices/Java Web Start.app", then choose always this as a standard option.