Panda Internet Security Won’t Install Right?

I am trying to install Panda Internet Security on my computer from a disc that I purchased from a local computer repair shop. We installed it on our first laptop fine, but when we installed it on the other one, it didn’t install correctly and there were errors and we could not activate the product.
I then uninstalled it from that laptop to start the installation process over, but when I try to install it again, it says that it “detects traces of previous installations” and there are just more and more errors and when it’s all done…same thing…can’t activate it, even with the correct customer code and everything.
I noticed that in my C drive, under Program Files, there is a Panda Security folder, and I’m trying to delete it so I can start over clean, but I cannot delete that folder. It repeatedly tells me I need administrative permission to perform that action, and I AM an administrator. I’ve tried many times and many different ways and I cannot delete this folder, and I believe that this is the “previous trace” that it keeps detecting when I try to install it.
Don’t want to take it back to the repair shop because he’ll charge a lot just to get this working correctly and we really don’t have that money right now. Any help or suggestions would be greatly appreciated. Thanks.