Two important restrictions

  1. The width of the window MUST be a multiple of 4.
  2. The width MUST be at least 108 pixels.

Minimum allowable width

Second restriction seems to be a characteristic of Windows Vista (or Windows in general)

Not possible to manually resize a window to make it narrower than about 108 pixels.

A Java program to display a frame with a width of 64 pixels displays a frame about 108 pixels wide. 

Note, however that the Java program doesn't hang up.