When running ISE on Linux 64 over an Xserver, Project Navigator exits with a Segmentation Fault when I select OK in the "Tip Of The Day" dialog box.
ISE stays open if I click the X on the top right corner of the "Tip Of The Day" dialog box instead of clicking OK.
This problem has been fixed in the latest 10.1 Service Pack available at:
http://www.xilinx.com/support/download/index.htm
The first service pack containing the fix is 10.1 Service Pack 1.