xfdesktop have a very very nice feature which makes it much like windowmaker; i have no task bar, the icons are the apps. unfortunately, when i got a long title the icon disappear, and also sometimes it blows and i lost my desktop. so i use the floating bar, which have a shortcut for terminal and invoke it again. i think if some sort of max size for labels where implemented it could be fixed...
Please run xfdesktop in gdb and get a backtrace. See http://spuriousinterrupt.org/projects/xfce4-debug
No response from reporter, closing.