I have found something, which I thing is a bug in the midnight commander.
If I set chmod of a file to 222, and later try to open it with the internal
editor (F4), there is a message that reading was not successful and contents of
a file is wiped. I use mc-4.5.55-7mdk on mandrake linux 8.2. It is rather rare
case, but can cause losing data.
with regards Ireneusz Dybczyński