Thinks there is an external monitor attached.

I inherited an iBook G3 14" (700Mhz) and installed Tiger and updated to 10.4.11. Now, every so often like the fabled dripping water torture, the screen goes blue for a couple of seconds as it does on my MacBook Pro when I attach it to a projector. Also, when I click on the menu bar "Displays" icon, there is a ghost VGA monitor with resolution settings showing up alongside (well, under) my Color LCD's settings.

I've just tried attaching the Apple VGA adapter a few minutes ago to see if that would stop the switching and so far, so good but I'm not exactly hopeful. Has anyone else had this problem? Any fix other than what I hope will work with attaching the adapter?

(btw, the adapter is not attached to any other cable or monitor)

Help...