This information should apply to Ubuntu as well as Xubuntu and applies to all LibreOffice v 4.x that I tried. If LibreOffice 4.x is crashing after the document has been open a few seconds, try opening the document but do not try to navigate at all. Instead, pull down the Font box and see if any of the fonts are set with an italics appearance (other than italics-based fonts). For example, if you have Comic installed, it should appear as itself and not in an italic font. If it does, the font is most likely mising from your system.
About Author: Brian