Well there is another thing to take into consideration.
All those software “data shredders” only make it harder to recover the data, but not impossible.
Specialized data recovery companies are still able to recover over 99% of the data as they use technic’s that go as deep as molecular level.
In case anyone is wondering if there is a workaround for the issue Eddy is raising, there is:
Drive a nail through the hard drive or melt/fry the ssd drive. 
or user one of these:
http://screencast-o-matic.com/screenshots/u/Lh/1493819857721-87077.png
http://screencast-o-matic.com/screenshots/u/Lh/1493819893289-2896.png
Before I go on a tedious fix of my C disk, I wonder if I can manually delete the plethora of files such as C:~090f C:~090. C:~093…etc. I feel of I delete these strangely named files, I may clear just about all of the problems, as they were all created in the same time span and day. Otherwise, I will just go through all the steps Avast support wants. I have been using my phone for internet as I am not at home very often. Thanks in advance for any advice!
I don’t see any reason why you can’t remove them. You may need to bypass the Avast Self Defense Module before you can remove these files.
http://screencast-o-matic.com/screenshots/u/Lh/1494164131495-33069.png
If this step was needed, be sure to again check this module to protect Avast from unauthorized changes.
Thanks all, used CC Cleaner to find and delete those space wasting files…gained more than 800 GB back again on my (C:)drive. Thanks to all for your help and advice. Avast should add a message for those wishing to cancell the shredding programs that doing so before complete may result in (C:) drive filling up with the shreds…or whatever. It was anniem’s recommendation from early in this thread that solved the problem😊
I am trying to solve the same problem. After shredding a file the file shredder hung at 90%. Now the C drive is almost full but I cannot find the files that shredder has created. The disk analyzer (windows 10) shows that 70% of the disc is used by “other” files but does not say what they are or where they are. Using CCleaner in safe mode does not delete these files. Can anybody suggest where I should look for them, or give an idea as to what they might be called. All sensible suggestions will be gratefully received.
The other user found his answer in this post:
https://forum.avast.com/index.php?topic=197250.msg1383278#msg1383278
Yes bob3160. I read that but unfortunately, as my first post states, CCleaner failed to find the files and therefore did not remove them. I need a clue as to where the files are and what they might be called to aid in my search.
Maybe this gives you the clue you need: https://forum.avast.com/index.php?topic=197250.msg1392082#msg1392082
Thanks bob3160 I think have read all the relevant posts on this forum after an extensive search but regretably they do not help. The files do not show in explorer. They seem to be in the root directory but I cannot see them. I was hoping that someone could give me an example filename with file path. Sad that the programmers of Avast have not responded to any of the posts from people who have this problem. There will be others and the solution needs to be found.
On another forum it has been suggested that I try SpaceSniffer and see if that reveals the files. I will try that tomorrow.
The files quoted were C:~090f C:~090. C:~093…etc.
They may be hidden files so be sure that your setting show hidden files. They would also all have been created on the day you used the file shredder.
Hidden files is enabled but sadly no such files show, no matter where I look or what program I use to find them. Avast seems to have created completely invisible files that have filled the C drive. I cannot delete what I cannot find. Back to my original post, the only clue is that 70% of the disc space is used by ‘others’, in disc analyzer.
Just in case anyone else falls foul of this atrocious piece of software (the Avast data shredder), the disc space has finally been reclaimed. The C drive was filled with invisible files in the root folder. Thousands of them all 200mb in size and beginng with a tilde, just as JeffVoodew posted. They did not show in Windows explorer, even with hidden files enabled. They were found using spacesniffer and then the disc analyzer of CCleaner located them in ‘other’. Finally they were deleted using a search and select for all files starting with a tilde on that date. Thanks to all on this forum who tried to help. No thanks whatsoever to Avast programmers who caused the problem and did not offer any support or help whatsover. Lets hope they have fixed the cause in new editions of the software.
TBH, daily management using CCleaner is sufficient.
As you found out, using a program such as this one has risks. Sorry for your troubles.
Just to clarify, the problem was the fact that you as a user interrupted the process which in turn caused the problem.
Had you allowed the process to finish, you would not have had all of those files left on your computer.
This same thing would have happened had you used another program that does the same thing and interrupted it.
Not true bob3160. Just to clarify, the program hung on 90% and sat for hours doing nothing! It was obvious that is was doing nothing the computer was completely unresponsive. There was not option but to shutdown. The file that was being shredded was tiny!
I don’t intend to argue the point with you.
You’ve solved it and moved on.
The file being deleted as a small folder of passwords, hence the nmeed for a shredder. The problem was an unfortunate error but it does not absolve the programmers of AVAST from resposibility in helping to solve it.
I am not arguing, just pointing out that you were not clarifying the problem, just making assumptions, which in this case were wrong.
End of matter. Now closed.