what is your Aperture version and what is your MacOS X version?
What happened, before this problem occurred? Did you import images, install software, move the Aperture library?
I have already uninstalled and reinstalled the library....Help!!
What do you mean by reinstalling the library? Did you reinstall Aperture?
You might start the trouble shooting with using the Aperture Library First Aid Tools - repairing the permissions, repairing the library, and rebuilding, if necessary, see:
Before rebuilding the library, make a backup of the Aperture Library, if you do not have one.