I have got characters like that in my notepad++
When i am trying to copy whole line, i am actually copying everything until \"NUL\":
File:1
I tried to use the \x00 and it didn't work for me when using C# and Regex. I had success with the following:
//The hexidecimal 0x0 is the null character
mystring.Contains(Convert.ToChar(0x0).ToString() );
// This will replace the character
mystring = mystring.Replace(Convert.ToChar(0x0).ToString(), "");