Why doesn't this short Applescript work on 10.9?

I had this short applescript, which worked fine on 10.6-10.7 to log me in to our office VPN:

tell application "Network Connect"

activate

connect to "x.x.x.x"

delay 2

tell application "System Events"

tell process "Network Connect"

keystroke "username"

keystroke tab

keystroke "password"

keystroke return

end tell

set visible of application process "Network Connect" to false

end tell

end tell

But on my new 10.9 laptop, it doesn't work correctly:

the Network Connect starts up, then one of my icons on the desktop has its name highlighted in blue (as if the cursor was editing its name) and the Finder locks up (spinning color pinwheel cursor) and needs to be Restarted. What's going wrong here?