I got TechTool Pro 5.0.4 with the MacUpdate Promo Bundle on the first day of sales. At first, I had problems booting up with the bootable DVD after burning it according to the instructions on my purchase receipt. The screen went completely blank after the grey apple and the loading animation below it at start up.
I waited a few days downloaded the disk image again but the situation was the same.
I also tested booting with other bootable disks like DiskWarrior and the Mac OS X Leopard disk to verify my optical drive is okay.

Finally, I checked out micromat.com's support forum for some insight. The following two solutions seemed to work for me:

1) Disconnect peripherals that aren't related with TechTool Pro's check.
2) Clearing PRAM from a cold start.

Links to the posts they are mentioned are as follows. The support team seems to be very responsive out there.

http://www.micromat.com/index.php?option=com_simpleboard&Itemid=42&func=view&id=5010&catid=6

http://www.micromat.com/index.php?option=com_simpleboard&Itemid=&func=view&catid=6&id=5020#5020

Now the TechTool Pro bootable DVD boots faster than even Apple's Leopard disk and the tools included are working wonderfully. I am a happy customer. Thank you, folks at Micromat and Macupdate for working to include TechTool Pro in this year's bundle.

I hope this will be of some help if, by chance, there are other people who have similar issues.