IMac :: OSX Boot Drive Corrupted - Trash Refuses To Empty?

1. I do occasional maintenance with onyx and have been getting a few startup disk errors in recent months. These seem to get repaired and the computer still functions as normal. I have never had these before in 8 years of using osx so they do worry me. Is the osx boot drive just a bit corrupted? Would a simple reinstall help or is the hd showing signs of failure?

2. The trash simply refuses to empty. The operation can�t be completed because you don�t have permission to access some of the items.

I've tried to bring the items back to the desktop and the folder they came from but they simply make a copy of them. I've tried the option key method and sudo rm -rf ~/.Trash + sudo rm -rf /Users/user_name/.Trash in the terminal but get no change