Now I have created quite the intriguing (to me, anyway) situation:
I have taken the library and .xml files with the list of songs and playlists, etc. that I want to keep onto a flash drive and let them refresh with a blank one in the iTunes folder (to make sure there's no trail of old information). Then I deleted all the songs out of the music folder, made sure the library location in iTunes was set to that music folder, and copied all my music back into that folder. Then I copied the old library and .xml files into the iTunes folder and overwrote the blank ones. The .xml file still said that the songs were pointing to a location on my external, so I did a find/replace on all strings to change the location to the music folder. Now the library loads right, the library in iTunes is set correctly, and the .xml file shows the correct path for finding the songs...but iTunes
still cannot find them! I really have no idea where it could be looking for these songs at this point.

Anyone got any suggestions?