I bought a macbook pro last month and loved it so i bought 21" iMac last friday. Both computers have a 300gb itunes database that are identical. The macbook plays flawless and fast thru songs, but the imac has 4-6 second delay in between playing music along with the spinning soccer ball, deleting anything from the library also takes quite a while. I did narrow it down that this only happens playing mp3 files only, aac files play fine with no pause and if i uncheck keep itunes music folder organized in preferences it corrects the problem. Any suggestions on correcting this and i do want my folder organized. My library is also stored on an external hard drive. I'm new to mac computers and a bit lost???????????????