Hi,
just in case you are working on the change tracking. Here is a simple recipe to crash LyX:
1. Create a new empty document 2. Activate "Change tracking" 3. Enter "bla bla" (leave cursor behind) 4. Open dialog "Merge changes" 5. Click "next change"
Assertion triggered in Change::Type Paragraph::lookupChange(int) const by failing check "empty() || pos < size()" in file paragraph.C:1691
Michael