The WriteProfileString will not generate an error.
Reasons:

• file is very small. the amount of information written is also very
  small.
  
• as user the file will only open during f.e. the time of the write
  operation.
  
• how many users are trying to write to that file at the same moment?
  we are using such structure for the creation of all kind of dynamic
  files, which contains much more information.
  only very slow server can be a problem for very great INI files, but
  your one will never be a problem for the server.