There are two bugs at work here.
Bug #1 using Memoir Class
Switching from book class to memoir to continue work on a novel works so long as I do not insert an Index. It complains with the following error:
LaTeX Error: Command \see already defined.
\newcommand*\see[2]{\emph{\seename} #1}
Your command was ignored.
Type I <command> <return> to replace it with another command,
or <return> to continue without it.
Removing the Index entry results in the error being resolved and View/export to DVI/PDF/HTML, etc works.
Bug #2 adding index entry after entering a return/enter newline call from the keyboard crashes LyX.
Scenario: Tested with Book class and Memoir class to rule out class specific issues.
On the last/current written chapter with the following layout:
Text included to help visualize the situation:
"I have felt this before. I musn't focus on the fire. I musn't focus on her twin,
[INDEX] Appendix A
If I put an index entry just after twin, of course it gives me the desired Idx tag to then name it so it knows where to reference the term, twin and from what page it is being referenced.
Now if I hit return/enter to get a new line within LyX and then go Insert->Index Entry then lyx crashes.
Here is a dgb reference that might be of value:
Label: Index Entry... Shortcut: I Accel:
Label: URL... Shortcut: U Accel:
Label: Note Shortcut: N Accel:
Label: Lists & TOC Shortcut: O
Found the pseudoaction: [177|algorithm]
Found the pseudoaction: [177|figure]
Found the pseudoaction: [177|table]
Label: Table of Contents Shortcut: C Accel:
Found the pseudoaction: [177|algorithm]
Found the pseudoaction: [177|figure]
Found the pseudoaction: [177|table]
Label: Index List Shortcut: I Accel:
Label: BibTeX Reference... Shortcut: B Accel:
Label: TeX Shortcut: T Accel: [C-l]
Label: Minipage Shortcut: p Accel:
Label: Graphics... Shortcut: G Accel:
Label: Tabular Material... Shortcut: b Accel:
Label: Floats Shortcut: a
Found the pseudoaction: [222|algorithm]
Found the pseudoaction: [222|figure]
Found the pseudoaction: [222|table]
Found the pseudoaction: [255|figure]
Found the pseudoaction: [222|algorithm]
Found the pseudoaction: [222|figure]
Found the pseudoaction: [222|table]
Found the pseudoaction: [255|figure]
Label: Include File... Shortcut: d Accel:
Label: Insert File Shortcut: e
Label: LyX Document... Shortcut: X Accel:
Label: ASCII as Lines... Shortcut: L Accel:
Label: ASCII as Paragraphs... Shortcut: P Accel:
Label: External Material... Shortcut: x Accel:
repainting 0,0 674,407
repainting 56,243 1,23
repainting 56,243 1,23
repainting 56,243 1,23
LyXFunc::dispatch: action[232] arg[]
repainting 56,243 1,23
BufferView::Pimpl::Dispatch: action[232] arg[] x[1076575562] y[138434328] button[138437344]
LyXFunc::dispatch: action[232] arg[]
lyx: SIGSEGV signal caught
Sorry, you have found a bug in LyX. Please read the bug-reporting instructions in Help->Introduction and send us a bug report, if necessary. Thanks !
-Marc