My anti-virus program was NIS (Norton Internet Security). I never saw this pop up in CCleaner's registry cleaner. My definitions subscription was up so I just switched to Norton 360 (a few more bells and whistles than NIS). I just ran Ccleaner and Googled for this topic. As suspected by others, I'd bet every penny i have it is related to Norton 360's way of doing things, probably the backup feature which NIS doesn't have.
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I wanted to hate Norton because way back, if you actually had a real problem, just to call them voice would cost an arm and a leg, and trying to find out how to email them was a venture in decrypting their non-instinctual website (they wanted you to figure it all out on your own, researching everything yourself). Some people used to say Norton's antivirus was flawed, but their product has never let me down and so I keep going back to Norton (since 2003).