Problem with PSE10 Edit Features Not Working Today?

I've used PSE since it started, but don't use many features. Primarily I use crop, enhance and sharpen. When trying to edit a few photos, I noticed that the enhance-lighting feature with histogram is not doing anything! Help, that is my number 1 tool. From either extreme, the photo doesn't change. Any ideas of what I can do. I restarted PSE and tried again with no luck?