It HAS been investigated, and it HAS been resolved.
The head of the Hawaii Department of Health confirmed on October 31 that Obama was born in Honolulu, saying that she has "personally seen and verified that the Hawaii State Department of Health has Sen. Obama's original birth certificate on record in accordance with state policies and procedures."
In addition, just a few days ago the U.S. Supreme Court refused to hear the case brought against Obama regarding his citizenship.
It's over. Quit bringing it up.