First of all i want to thank you for a great program. Keep up the good work.

Here's an idea. What if you added a feature to kill a prosess, and\or maybe schedule files for deletion on next boot. Those would be practical for a cleaning program
Or what do you guys think?

Yes, it would be a useful feature.

For now use unlocker I've been using it for years now, and it is very handy to delete those files still in use.
http://ccollomb.free.fr/unlocker/

As Fireryone states Unlocker can be very useful. Another possibility to get rid of stubborn files is FileAssassin by Malwarebytes. Haven't used FileAssassin myself though.

For a process killer, you could take a look at Darkspy, which is actually an anti-rootkit, but includes a powerful process killer.

Why are you wanting CCleaner to kill a process? I'm not sure if a process killer is practical for a cleaning program. But I guess depends on how you look at it. And unless something changed recently that I'm not aware of, CCleaner does schedule .dat files for deletion on next boot. Are there specific files in mind that you are suggestion to be deleted on next boot?

No i dont have this problem, but i thought it would be nice to for example schedule a file for deletion on next boot. I was thinking on basicly all files, not just .dat.
The "options-custom-add file" only removes the selected file, not on the next boot, ans so it won't remove files that are in use. (viruses, exe-files, some media files etc)
I agree the kill prosess thing, is a bit out of order, but you could for example use it to kill the prosess using the file, if youre too lazy pressing "ctrl+alt+del". We like all in one programs:P
But serious the schedule file thingy, could be a nice feature.

However scheduling certain files to be deleted on reboot such as certain logs like Windows Firewall (pfirewall.log) and Task Scheduler (SchedLgU.Txt) or files/folders someone adds into Options->Custom would negate me having to use a rival freeware cleaning tool that does delete any in-use locked file on reboot.