I finaly found out why the client kept crashing at several machines. It turns out, european regionals settings have the "decimal point" replaced with a "decimal comma". This causes second life to crash when starting the graphical engine.
Steps to reproduce the bug:
In the regional settings in windows
Set the decimal seperator to , (comma)
Set the Digit grouping symbol to . (point)
Observed results:
Game crashes during "initializing world"
log-file contains error about unconnected bones in avatar.cpp