Paul A. Rubin wrote:
The easy solution is to put Acrobat Reader's directory on your system path and leave the viewer setting as 'auto' in LyX.
Actually, I'm not even sure you need AR on the system path, as long as it's in the registry as the default viewer for PDFs. The 'auto' setting is AFAIK the default when LyX installs. Did you change it for a particular reason (such as AR *not* being your default viewer)?