The point of CCleaner is to remove all Sims 3-related entries from your computer's registry. The registry entries are different for disc and Origin installs, and it may be that a leftover Origin-related entry is causing the problem. I suppose if you had previously installed the EA Download Manager and hadn't effectively removed it, that could be the cause as well. But I don't know how the EADM works, or how you would go about removing it.