I'm using version 0.9.0 build from ports on Freebsd. Thunar makes my system reboot if I do the following: Open Thunar show hidden files with ctrl-h, mark a hidden directory (.something) open a terminal window and make rm -r .something. Switch back to Thunar and be sure the directory is still marked, press F5 to refresh. After some seconds my system restarts and I can see mentions of a segfault.
Works fine here. Can you provide a backtrace if it's still broken?
I tested with version 0.9.3 of Thunar and it works now :-)