Spybot not installing-Error five access denied

[Jehat]

My computer recently got infected and I was able to clean right away using Spydoctor and Adaware. Spybot was also recommended so I wanted to add that as well but it will not execute the installation and I get the above error- Error Five, access denied. I then loaded up Malwarebytes and all three programs run fine but not Spybot. In addition, I find nothing in safe mode or in full mode after full scans from each. It makes me think there is still something there or some residuals are somehow affecting Spybot and not the others for some reason. And yes, all the other programs are off when I run each one and when I try to install Spybot.

I haven't included the log files yet or backed up the registry as I just wanted to ask the question to see if there is something simple I could look into to fix and allow Spybot to install. Interestingly enough, the Amazon digital down loader won't install either so whatever is ailing Spybot has this one jammed up too.

Please let me know your thoughts and I will be glad to include the files if it is necessary. Thank you.

[Jehat]

I was able to load Malwarebytes in safe mode and it actually picked up a couple of trojans that Spydoctor and Adaware did not. I was able to then load up SpyBot. Thanks anyway.