<hr /><i>anonymous claiming to be mgagnon added on 2011-01-25 21:22:31 UTC:</i><br />
It seems that the problem happens when a file name is shorter than another, but all the characters are the same as the longer one (first characters).

<b>example:</b>

  *  <b><em>test.c</em></b> and <b><em>test.cpp</em></b>   will cause the problem
  *  <b><em>test.h</em></b> and <b><em>test.c</em></b> will be ok
  *  <b><em>test</em></b> and <b><em>testt</em></b> will have the same problem

So it's not really related with extension...