This, I'm afraid, in my experience is the wonderful world of Apple. My late 2010 27" iMac has been a constant source of stress (my first and definitely last Apple machine).
Among the myriad of problems the Finder is another constant source of annoyance. I have a NAS attached - the most advanced OS in the world (Apple's words) is incapable of dealing with it. The finder either freezes totally or just does not show the contents of the folder on the drive (accessing via a Windows machine has no problems at all). Oh, of course, don't expect spotlight to search the NAS - it is incapable of doing this.
In my view the OS is flawed in too many areas to cover. But, frankly, an OS that falls down as frequently as Lion, Mountain Lion, etc does not deserve to be viewed a favourably as it seems to be.
I am sorry I cannot offer a solution here - there doesn't seem to be one. And before the Apple faithful come up with arcane measures that involve commands in terminal - that is not good enough. The OS should just work - particularly it's essential and basic feature - a reliable file management system being a core requirement.
I realise that these forums are not monitored by Apple - they should be for goodness sake.