Hurricane
Wiping free space will not harm your computer nor will it cause programs to stop running. Wiping free space on your drives simply gets rid of any left over bits and pieces of files that are left behind. Kind of like how your wife goes behind you with a roll of paper towels getting rid of all the streaks after you have cleaned the windows.
While CCleaner can be used to wipe free space, there is a much better program to do it.
Eraser. A nifty program by Heidi.
http://eraser.heidi.ie/ Go to the Downloads tab and scroll down to Stable Builds and select version 6.08.2273. That is the most recent stable version...works like a charm in Win XP and Win 7 64-Bit Home Premium and Ultimate (the only versions of Windows I have run it on...should work just fine with Vista as well).
Here's how to effectively use Eraser.
1) Stop sending files to the Trash Can/Recycle Bin thingie. Deleting a file does not get rid of it...it simply tells the computer to ignore the file, while the file remains on your disc until it is eventually over written by another file. Kind of like taking down the mail box to your house...the house is still there, but you can't get any mail. Not at all secure.
Eraser allows you to ERASE the file completely and permanently....once you have Eraser installed, all you have to do is right click on the file(s) you want to get rid of, a pop up window thingie comes up, select ERASE. Bingo Bango....Eraser will overwrite the file 1, 3, 5, 7, 15, 35 times...what ever level of secure file destruction you desire.
2) Using Eraser to wipe free space is far better than using CCleaner as it will get into all the little nooks and crannies and totally clean your HD of any residual file parts and pieces...all the way out to the cluster tips. I have no idea what this means other than it frees up HD space, cuts down on read/write times, reduces the likelihood of trojans and worms hiding out in those nooks and crannies and keeps you HD clean and shiny.
It's free, it works like a charm. I install it on every computer I work on and show the owners how to use it and why they should use it.
It does take a while to fully wipe the free space on HDs. So, I suggest firing up Eraser, starting the Free Space Wipe, and going to bed...let the system run all night and do its thing.
OBIO