SureThing locks up during installation. This usually occurs during installation of the Accent font.
Another program is locking out access to this already installed file, so SureThing is unable to overwrite the file which causes the lock up.
To fix this, reboot your computer in safe mode with CD-ROM support. Now install the SureThing software. Reboot normally.
Rebooting in safe mode is usually accomplished by pressing the F12 or F8 key as the computer is starting up but before the OS starts to load.