My hard drive on my powerbook g4 filled up, and I purchased a seagate external hard drive for extra space. I moved about 40 gigs of files over to it, erased them from my hard drive, emptied the trash, and the internal still has no space. All the files are on the external, but they don't show up on the internal. How do I get the internal to realize these files have been moved and it has 40 gigs of space available?