Had no problems for the first five months I've had my 27" i5 iMac watching videos in iTunes. In fact, it was a dream because the video was always as smooth as it gets. Over the last few days, however, iTunes has developed a problem where I simply cannot watch videos in it anymore. It'll play for 10 minutes, then it starts freezing for seconds, then minutes at a time. It'll unfreeze for 5 seconds, then freeze again for 30 seconds. What's even more frustrating is that the video on the hard drive keeps running so when it unfreezes 30 seconds later, it shows the video 30 seconds ahead. Also, if I force quit while iTunes "not responding," it doesn't do me any good because when I reopen iTunes, it just tells me that the drive (external hard drive) that the iTunes folder is on is locked, which isn't true. Only way to get iTunes to open back up again is to restart the entire computer. Any idea what's causing this? It's a serious problem because I'm always buying TV shows and movies from the iTunes Store and I can hardly watch anything now. EDIT: Double checked that the issue was only with iTunes by playing an hour long video in Quicktime and it's indeed isolated to iTunes. Had no problem when playing the video in Quicktime.