Hi
Vick - not sure if this will help, but I would first try to 'Force Close' the iBooks app, i.e. open the multi-taskbar (double tap the home button or use the multi-gesturing movement, if activeated in iOS 5); find the iBooks app, press and hold until it starts jiggling, then hit the minus button - return to the home screen and try iBooks again - let us know if that works.
If not, then you might want to 'Restart' and if not successful 'Reset' the iPad - directions
HERE if not familiar w/ the maneuvers - good luck and post back if none of these suggestions solve the problem!
P.S. - welcome to the forum!