Another cookie deleting program (Maxa) listed "silverlight cookies" upon completion of a trial search. From what I see CCleaner does not seem to clean these cookies and I was hping it might be a new addition in a future version.
I have had no problem on my own computer but had problems with two new Vista computers. The large files beginning with a "{" caused a defrag Failed message. By un checking only those files I was able to complete.