I've seen this error posted in the experimental windows topic but it seems to be solved in the latest win32 build. In my linux build from today i still get:
XML Parsing Error: undefined endity
Location: chrome://communicator/content/pref/pref-fonts.xul
Line Number 67, Column 49:
<menuitem value="x-devanagari" label="&font.langGroup.devanagari;"/>
--------------------------------------------------------^