Karen, are you by chance using Bluetooth headphones or speakers? If so, try the following:

press insert+numrow 6 which will call up the settings center of JAWS (that's the number 6 above the letters),
press control+shift+d to load the default (all applications) settings,
type the word avoid and wait until you hear JAWS announce Avoid speech cut off when using Bluetooth headphones or some sound cards,
down arrow once, and if the setting is checked, press the spacebar to uncheck it.
press enter twice.

The description of this setting: Many modern Bluetooth headphones and speakers shut down after a while of not receiving sound to conserve battery. If this check box is selected, JAWS will keep them awake by constantly playing silence. You will not hear anything, but your device will remain active, resulting in more consistent speech. Note that the battery of your headphones/speakers could drain faster if you turn this on.