when i say cancel, i mean it!

I had installed McAfee security center and wanted to rid my computer of all the junk it had accumulated over the years. First, the installation slowed down my PC to a near halt as my laptop is a pretty old one with just 512 MB RAM. Then, it took ages to start up security center.
I chose the option for "Quick Clean". Then, i got the below window saying "Cleaning in progress..."

I waited. I waited a bit more. I waited a lot more. I got frustrated and did the obvious, pressed the cancel button. I decided that it just wasn't worth the time to rid my computer of all the evil! Then, the below window showed up, "Cancellation is in progress. Please wait..."

I waited. I waited a bit more. I waited a lot more! I really got frustrated. Now, i wanted a "Cancel the cancel" button! What did the programmers think while making this installer? Isn't "cancel" supposed to mean "I have had enough of this. Just get the hell out of the installer"?