I started demoing photoshop lightroom a couple days ago. The program is running very sluggish when I am trying to edit. I had the same problem last night so I uninstalled and reinstalled the demo and it worked great last night. When I opened my program this morning it was sluggish again.
Make I know do you also receive any error message as well.
I did for a minute after I quit the program then restarted it. I quit and restarted the program again and the error sign was no longer there.