Update 2012-07-25: see the application signing notes.
Mac OS X Lion and Mountain Lion have a “sandboxing” feature that prevents my testing software DiskTester (part of diglloydTools) from accessing the boot drive (system drive) for its various tests. A workaround fix is planned.
The workaround is to run the command line (Terminal) version of DiskTester using 'sudo', which will prompt for a password and thus allow permission. Be sure to install the command line tools first (found in the diglloydTools folder once installed).
Start Terminal, then use sudo as shown in this example (using your own desired command):
diglloyd:~ lloyd$ sudo disktester recondition "Macintosh HD"
This technique works for most permissions errors (when Mac OS X denies access to a program, typically -5000 error, this is not specific to DiskTester).
You can use the Launch As Root program to launch the DiskTester GUI with permissions suitable for getting the test done. I’m definitely not a fan of giving anything root permission, but this gets the job done.