Yes I am getting this as well.
I changed the browser path from "null" to "/Applications/Firefox.app" and the problem went away. However, it still launches in Safari. Hmmm..
Also when I quit it doesn't terminate the processes. i.e. these are left running:
501 4312 200 0 2:38PM ?? 0:00.09 /Applications/SystemManager3.app/Contents/MacOS/SystemManager3 -psn_0_1458532
501 4314 4312 0 2:38PM ?? 0:05.17 /usr/bin/java -classpath /Applications/SystemManager3.app/Contents/Resources/WebServer -jar /Applications/SystemManager3.app/Contents/Resources/WebServer/SystemManager.jar
I have to kill them before I launch System Manager again.