Music stops between songs?

Question

There's a huge thread that tried to address this problem, but it's almost completely useless because of the myriad other problems mixed into the thread.
For three years, itunes has had problems playing my music.  In between songs, it hangs about 3 seconds into the next song, whether I'm listening directly on itunes or streaming to my AppleTV.  If I go next and back on the controls, that song will start playing, so the media is not corrupted.  I've patched every component in my setup for years, and it's never been fixed.  There are no errors or error logs to check (thanks Apple).  This problems comes and goes, but it almost always happens when I have guests over.
My library was on an external Hard Disk in a USB enclosure, which is a supported setup according to Apple, but I believe it's the source of my problems.  I moved my entire collection to the internal HD and the problem is now gone.
My theory, which seems to fit with a number of other people's set up and problems, is that some hard disks are set to 'spin down' after a couple of minutes to save energy.  When itunes tries to acces the next song, it times out waiting for the disk and just freezes.  I've tried to keep the disk spinning, but disk caching seems to defeat my methods.  If you have a NAS or external HD and have this problem, I believe that's the root cause.
If anyone else has a similar setup that wants to chime in, please do.  Keep in kind that this may be OSX specific, and that some external HDs may have a default spin down setting long enough to prevent the problem.  If you have a different problem with itunes, please don't flood this thread with variations unless they are relevant.

Answer 1

I have same issue. I have all music stored on a Network Attached Server (NAS) and I can upload new music to this location fine over my wireless network. I can also edit information about each song within iTunes, although I have to put up with a spinning beachball sometimes while iTunes is having a think.
I never had drops before, but now the audio cuts out even though the track is still playing - as seen from the progress bar in iTunes. So some information is being streamed but sadly not the audio portion - reliably at least. And the Aiprot signal is strong.
There doesn't seem to be any rhyme or reason to it:  bought downloads, files ripped from personal CDs or my mp3 rips from vinyl. Whatever the type of file, Airplay has an intermittent problem. In fact it's not just intermittent (cutting out at regualr times such as the end of each track). It's RANDOMLY intermittent. Sometimes you get a whole track without trouble, other times it drops every 3, or 10 , or 60 seconds. 
It's like Apple have introduced a roulette plug-in to Airplay. Fun, huh? 
It's incredibly frustrating given that a) I had no such issue with Airtunes on previous computers b) I just bought a new Macbook Pro and c) Apple market this functionality to consumers as part of a home entertainment set-up, and that's not really happening for me right now.  My set-up is effectively useless and my chance to impress dinner party guests has been blown (kidding). 
At first I thought it might be a hardware issue with the Airport receiver inside my new Macbook Pro but that doesn't stack up: I have no other issues using my wireless network on the new laptop - as I say organizing music within iTunes or doing anything else wirelessly such as streaming from YouTube, works fine. 
I do hope someone from Apple is listening because I think Airplay requires a patch. That's my hunch.
Macbook Pro 13" Intel Core 2.3 gig i5
OS X 10.6.7
iTunes 10.2.2
Airport Express 802.11n v 7.5.2
NAS: Western Digital NetCenter