I've searched, but couldn't quite find the answer. I have an external HDD connected to my Airport Extreme. This HDD shows up as a shared drive on my Mac and my Windows 7 PC. The iTunes library is on there. Both iTunes on the Mac and PC are pointed to the right place for the library. However, when I open iTunes on either machine, they go through a huge "checking/updating library" phase, which takes about 30 minutes. During this time iTunes is frozen. When the library becomes available, everything has a ! icon next to it, and when I check the library path it has changed to /iTunes media instead of just /iTunes. I change it back, it finds the files, but it'll reset itself again next time. Is there any way for two computers to share the same library, or do I need to do it via Home Sharing? But with Home Sharing, that means iTunes needs to be left running on one machine, doesn't it? Which for me isn't practical. Is there something preventing multiple computers accessing a single network library of music? I used to work in an office which had a music share, and it worked fine, although that was all Windows machines and wasn't using iTunes.