plotting window will not open

[CryptoLevel9]

I am using Octave version 2.1.57 and Gnuplot 4.0.0 on a Windows XP Professional computer through means of Cygwin version 1.5.10-3.  When using either Octave or Gnuplot I cannot plot anything, they both indicate that something has been plotted when I tell them to plot but no plot window ever comes up.  Any assistance that anyone could give me would be greatly appreciated.