to me this sounds like a software problem, or perhaps some corrupted file somewhere. it sounds like the Finder is crashing when you try to access top level directory of your hard disk. I've heard of problems where a corrupted .DS_Store file or some other user file on the disk causing Finder to barf when it opens the containing directory
I assume that you can run other applications and do other things on your Mac without problem. Do you notice any other symptoms?
Here's a couple things to try before you resort to replacing your hard drive
1) Can you open other folders in the Finder? (press Cmd-N to get a new Finder window, then navigate from there...)
2) open the Console (since you can't open your hard disk, you may need to launch the Console app by first searching for "Console" in Spotlight, then hitting return
With the Console open, cause the Finder to crash and then take a look for any clues in the console listing
3) perhaps try running Disk Utility (again, you may need to first find it in Spotlight in order to launch it) - try repairing the disk and/or repairing the permissions to see if that helps
4) does the problem still occur if you create a new user, then try to open the hard disk logged in as the new user? (just to make sure there's not something wonky with your user and settings)
p.s. if you are suspecting your hard drive is failing, do you have a backup already?