Sirs, I encountered a particular loop while installing LyX 1.3.6, which I thought might be useful.
I installed gsview and acrobat, first in C:/Program Files/Ghostgum and C:/Program Files/Adobe, and then again later (trying to solve LyX path problems), directly into C: The loop was this: 1. In Edit->Preferences->File Formats->{PDF (dvipdfm), Postscript}-> Viewer I would manually insert strings "acrord32" and "gsview32" and "Modify" 2. This worked, View->->{PDF (dvipdfm), Postscript} became functional (LyX could find the executables) 3. I ran Edit->Reconfigure, 3.b. configure couldn't find the viewers (they were not in the path used by configure) 4. configure re-wrote the preferences file, and the viewers quite working. 5. Repeat, (reinstalling and moving viewers, etc). What I found was that I had to manually install the paths to the viewers in the environment variable PATH, at Control Panel->System->Advanced->Environment Variables. What is striking is not so much that the viewers were not found and were lost, in steps 3 and 4; but that "acrord32" and "gsview32" were in the path used to execute the viewers in step 2. This seems to imply that the execution from LyX operates with a path that includes directories not included in the path used by configure. Two possibilities that could add value a) Form the conjunction of the path currently used by configure with the path by which executables are found (these should no doubt be the same, I don't know if mine are different because I've deranged things or because paths are handled in unstable ways by Windows), and run configure using this larger path (or maybe the path used by configure should be simply the path known to the executing LyX). b) When reconfigure is going to delete an executable from the configuration because it isn't found; test for it first by trying to execute it (e.g., before deleting "gsview32" as the postscript view, try executing it from LyX (maybe not from the configure script)). A totally separate item, Just to pass it on, I was totally fooled by the grayed-out "ispell" in Edit -> Preferences -> Language Settings -> Spellchecker and kept trying to get Aspell correctly installed long after it was installed correctly. If the "Spell checker program" box woke up and said "Aspell" when Aspell is found, that would be helpful. Finally returning to the line "check spelling if you installed Aspell, with Edit->Spellchecker." in the install notes, and realizing to directly test the spellchecker; I felt like Gandalf when he deciphered the line "Speak Friend and Enter." Thanks Brian (LyX user since 1998)