Can't install CCleaner v5.04 as Administrator!

My windows 7 computer has three accounts. Two regular user accounts and an administrator account. I am administrator, but use one of the user accounts for web browsing.

I attempted to update CCleaner (free version) after logging on to the administrator account.

Downloading was fine, but when I went to install version 5.04.5151 (64 bit) it gave me the error: "CCleaner v5.04 setup

error opening file for writing".

According to your FAQs, this error says I need administrator permission.

I WAS logged in AS Administrator. I gave permission for the program to make changes to my computer. It STILL gave me the error!

I switched to my regular user account, and downloaded the file.

I told it to run the file. I was asked for the administrator password, and entered it. the program installed with NO PROBLEMS!

Is this a problem with CCleaner or Windows 7?

Windows 7 Pro (64 bit) up-to-date as of April 06, 2015. ( SP-1 and ALL non-optional updates installed)