I have been using the cleaner for a year or more and no problems...UNTIL I decided that the guttman wipe was taking too long and I opted to hit the cancel button. It was wiping free-space at the time. I am contacting you via my "new" computer which I just got up and running.
When I tried to boot up the next day with the old system, it would not launch windows, even in safemode. Took it to the shop. HD had fried sector. This problem occured the very next session after cancelling the wipe of free space. I had no previous boot problems or system problems for that matter. Be very careful. This mistake costed me 200 bucks.
At this point, I am afraid to run cccleaner on my new system. Just thought you all might like to know about this.