I use ccleaner , wise care 365 free and privazer , I only use privazer once per 2 or 3 three months to clear out old prefetch data and for cleaning the free space and mft files. and to answer moose's question : I run win 8.1 64 bit and privazer does the job for me. als cleaning programs use different cleaning cycles and what one does not find , the other does. I do not recommend privazer for people who do not exactly know what they doing , but it does not mean that privazer is not an untrustworthy program. it actually quite good.