Comment 2 for bug 1164028

the main issue appears to be that the KVM instance is being launched via Popen using shell=true, which isn't necessary. This causes it to launch in a subshell that grabs user input from the calling shell (the one running checkbox) and never releases it (because of the secondary issue below). I've fixed this by simply removing shell=true from the bit that launches the KVM instance of the Ubuntu cloud image.