i'm not a big time mixer at all, by any means - but still a lot of what is being said here rings true.
the worst things are getting stuff to work on that is a complete headache because of crappy 'file management' - for pete's sake, keep it tidy!

there is nothing worse than finding a load of stuff missing / badly labelled / surplus to requirements / sprayed everywhere.
one of the other bugbears is finding out some track uses some stupid plugin you don't have on your system, then be expected to install a shady copy on your nice clean system, just to get it working - hasn't anyone heard of bouncing tracks?
another one is getting dvd's with the audio files on that are either a) cheap and nasty and therefore won't read on my drive or b) badly handled and therefore scratched.