I am running a trial copy of Adobe Captivate 5. My output is Flash SWF/HTM. My operating system is Windows XP.
Selecting "Custom Size" and "Automatic Panning" results in a severe slowdown in Captivate. Whatever is slowing down my machine also pretty much kills Task Manager, so I can't use it to close Captivate. I have to force reboot my computer.
Have you tried upgrading to 5.5. I haven't used panning yet but was interested, but curious if this was just a 5.0 problem