I started from Lightroom 4 and did a merge to HDR. All the images opened in Photoshop CS6 HDR. (Unlike CS5 there was only one tab called Untitled HDR) The HDR control panel opened up and I edited the highlights shadows and removed ghosts. I clicked to finilize the process. The panel closed and I find myself looking at a PS CS6 screen with no image open at all. I went to LR4 and looked around. There was no stacked image. There was no imported image. I sorted all edited images. It was not there. I went back to PS CS6 and and tried again only I changed 16bit to 8bit. Still nothing. I had Google Chrome running and nothing else. I am using a iMac running 10.7.5 with 4 gigs of ram. Nothing ran slow. Everything ran smoothly and/or quickly.
I just opened Adobe Aplication Manager and saw an update for PS CS6. I just became an Creative Cloud member a week ago. I hope this update corrects the problem!?!