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U need to be at a dos prompt to do this properly, It may be neccessary to add ansi.sys to your startup files.
If you do this in explorer or file-manager then others will be able to access your files more easily.
First make sure U can do this: (hold down alt and type 255 on the numeric keypad as indicated)
md alt+255
cd alt+255
Now U can type cd\ or cd.. and then DIR you will see a directory called [ ] The space in the middle is called null
it is
made via alt+255. Now for the fun bit !!
You can put text after the null character, which will tempt people to open it e.g. [ doom] where the space before the word doom was created via pressing alt+255
I'm sure you can think of more tempting stuff to put as the directory name. You may feel it neccessary to put directory's like these on computers in shops, and then wait to see if the dumb sales assistants can delete them !!
The only way (as far as I know) to wipe a directory named via the null character if you don't know about alt+255, is to type deltree *abcd where abcd is the directory name which follows the null character.