I always get a crash when clicking "options" in the message dialog, independent from savegame and pak.
EDIT: This bug may come from ST-standard, reported here (http://forum.simutrans.com/index.php?topic=1897.msg19668#msg19668).
This does indeed come from Simutrans-Standard, and the fix for this (from the trunk) is incorporated into the latest release of Simutrans-Experimental, now available.