Graphics Disappearing

I'm hoping that someone can help me. I created a document in RoboHelp HTML with graphics. Up until today all my graphics displayed in my printed documentation. Today they will not display in the printed document. I have not touched the graphics. They display in my xml output. To try and work around the problem, I deleted the graphics and reinserted them... they still do not display. I then created a new tag that says to display in printed document and online document but they still do not display. I'm running out of things to try.