No longer powers down after shutdown since upgrade
I have a Dell Vostro 1500 laptop. I've been running earlier versions of Ubuntu (dual-boot with Vista) on this laptop for for over 2 years without issue. Since upgrading to 9.04 (It may have worked the first couple of times, I don't remember) I have been having an issue where upon shutdown (clicking the red icon then selecting shutdown) Ubuntu goes through the normal shutdown process, but when i gets to the point at which the laptop would normally power down, instead the screen turns back on (just empty black screen), and it just sites there.
Does anyone have any ideas as to what might be causing this, or how I can troubleshoot this issue? Thanks in advance.