Copying lots of music files at once

Question

Sorry if this has been asked before....but I'm trying to move around vast numbers of music files between areas on my MacBook Pro and if I try and do too many, it won't let me.
For example, I have 2 users set up on my laptop. One is the main user and the other is for a spare iTunes so I don't have to delete files when the iPod gets full - I can just move them about. So I occasionally move a number of files between the 2 by copying from one iTunes to a drop box and then going to the spare user then copying them again to the iTunes for that user. Sometimes it'll let me do 1000 or more songs, but other times it gets stuck at around 50 or less.
AND I'm trying to back up ALL of my music files to an external drive. Obviously I want to just drag and drop as many as I can (i.e. 1000s!) and leave it running while I do other stuff, but again it won't let me.
Any ideas? Is there a limit to how many files /GB you can move? It's weird as when I first got the MacBook Pro I backed up the music straight away to a spare drive and I'm sure it worked ok without having to do a couple of hundred at a time or something like that.
Please let me know if you can help - thanks!

Answer 1

Thanks Matt.
In response...
"First of all, I have to say that your method of managing iTunes seems a little complex. Wouldn't it also work just to manually manage iTunes (instead of automatic updates) and then you can move whatever songs you like to the iPod?"
I prefer to sync and not work manually. Easier for me to do than manage songs individually. I have a full 80GB iPod - manually managing isn't something I really want to do. I've got about 85GB set up in the spare user account also. The spare user is basically there for music I doubt I'll want to listen to for ages but don't want to delete. If I had 150GB in the same iTunes and was manually picking out tracks, it would kill me! I know that works for other people, but not for me.
"When you move files around, are you moving a single top-level folder, or multiple files or top-level folders? I've found that moving a single folder (that may itself contain hundreds of items) is more efficient than trying to multiple-select and move the enclosed items."
I'm trying to move multiple files from iTunes to a single folder. I hear what you're saying, but basically I have a playlist of about 1,200 songs that I want to move from my MacBook to the external spare drive, and also want to move about 500 songs from one iTunes to another. I know what you mean, but I need to be able to copy from from iTunes to a separate folder all at once.
Maybe if I was able to export playlists from one iTunes to another that would be easier? I used to do that on a PC and it worked fine, but can't get it to work on this Mac.
Anyway, I don't understand why it's not an easy task to simply copy a number of files from one location to another, regardless of amount or size....shouldn't be THAT hard should it?
To do what you suggest, I'd need to have moved the files into a top level folder in the first place and that's what I'm struggling with I think....any ideas?
Thanks for getting back to me - appreciated!