title: Python crashes when using call (ntdll.dll)
body: <p>I have a script that combines around 1000 files by using an external program. It does so by copying the first file to <code>combined.sym</code> and then combining the this file with all other files, one by one. Code is as follows: </p>
  
  <pre><code># gets all .sym files
  symfiles = []
  onlyfiles = [f for f in listdir(myPath) if isfile(join(myPath, f))]
  for f in onlyfiles:
      if '.sym' == splitext(f)[1]:
          symfiles.append(f)
  
  # copies one initial combined file (point to start from)
  combinedFileName = "combined.sym"
  copyfile(myPath + symfiles[0], myPath + combinedFileName)
  for sym in symfiles:
      print("processing " + str(sym))
      cmdString = combinedFileName + " "
      cmdString += sym
      cmdString += " -a " + combinedFileName
      finalCmdString = r'cmd.exe /C fuseFiles.bat "' + myPath + '" "' + cmdString + '"'
      call(finalCmdString)
  print("done")
  </code></pre>
  
  <p>The batchfile I'm calling looks like this, but that is not the issue:</p>
  
  <pre><code>@set PATH=\path\to\executable\;%PATH%
  @cd %1
  @FusingProgram "%2"
  </code></pre>
  
  <p>Now, when I run this script, it runs for like 15 Minutes before it just stops and returns to the CMD.</p>
  
  <pre><code>processing onefile.sym
  processing anotherfile.sym
  processing evenmorefiles.sym
  processing yougetit.sym
  
  C:\Users\test\&gt;
  </code></pre>
  
  <p>As you can see, it misses the "done" print, and it didn't process all files. The <code>combined.sym</code> is created and expanded by the other <code>.sym</code> files </p>
  
  <p>When checking the Windows events, I can see, that it logs python as crashed and lists     <code>ntdll.dll</code> as faulty module(sorry for german log):</p>
  
  <pre><code>Name der fehlerhaften Anwendung: python.exe, Version: 0.0.0.0, Zeitstempel: 0x53787196
  Name des fehlerhaften Moduls: ntdll.dll, Version: ****, Zeitstempel: 0x5b6db230
  Ausnahmecode: 0xc0000005
  Fehleroffset: 0x0002e2eb
  ID des fehlerhaften Prozesses: 0x6224
  Startzeit der fehlerhaften Anwendung: 0x01d454e0ff20377c
  Pfad der fehlerhaften Anwendung: C:\pat\to\python\python.exe
  Pfad des fehlerhaften Moduls: C:\WINDOWS\SysWOW64\ntdll.dll
  Berichtskennung: 8b4254f0-c0d5-11e8-9a6f-901b0e5a6206
  </code></pre>
  
  <p>I've done some research and it seems like I'd have to resolve this by updating the ntdll.dll file, but my system is all up to date, so there is nothing I can do about that (except for downloading another version from some untrustworthy site, which I'm not gonna do)</p>
  
  <p>All this being said, have you ever encountered a similar issue or is this just a stupid mistake I made?</p>