DES sample crashing Windows 7

I ran the prebuilt DESTester.exe, copy the following files to a clean directory


and renaming

des-xem6110-lx45.bit to destop.bit

Then I ran

E:\destest>DESTester.exe e 0123456789abcdef in.txt out.txt
---- Opal Kelly ---- FPGA-DES Application v1.0 ----
FrontPanel DLL loaded. Built: Mar 13 2011 17:15:39
Found a device: XEM6110-LX45
Device firmware version: 1.0
Device serial number: 11420000QN
Device device ID: Opal Kelly XEM6110
FrontPanel support is enabled.
DES process succeeded!

and that worked. Then I ran the

E:\destest>DESTester.exe d 0123456789abcdef out.txt in2.txt

and my CPU hung. I can’t paste the result, since the CPU hung! If it happens again, I’ll post the result from a different computer…

What can I do to debug this?