error ?
 

Unknown Error: mscorlib
at System.IO.__Error.WinIOError(Int32 errorCode, String str)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, Boolean useAsync, String msgPath, Boolean bFromProxy)
at System.IO.FileStream..ctor(String path, FileMode mode)
at WindowsApplication7.Form1.GetFileMD5(String FilePath)
at WindowsApplication7.Form1.DownloadExtras()
at WindowsApplication7.Form1.DoUpdates()
at WindowsApplication7.Form1.Timer3_Tick(Object sender, EventArgs e)
at System.Windows.Forms.Timer.OnTick(EventArgs e)

Is this something you get often, or just something you got once? It seems the microsoft code is struggling to get an MD5 hash for a particular file. If it only happened once i'd personally just ignore it. If it happens a lot or happens again then I suggest you go into the auto-updater options and select "re-download all files" button, as at a guess I would say one of them is slightly corrupt.