Whenever I try to run Populous TB I get the missing registry message. It goes like this:

"Missing or incomplete Registry information. Use C:/POP3.CD as default hard drive path?"

If I choose "no", the window closes. If I choose "yes", another error follows: "A 3D device with the required capabilities could not be found. If you do have one, please consult the Troubleshooting section of the Reference Card. Otherwise, run the software version of Populous: The Beginning".

Any clues on how to solve this? Thanks in advance!

first error: Try reinstalling Populous, it may have been interrupted by anti-virus programs.

second error: What graphics card do you have ? If it's an AMD/ATI card, you need to update the atiumdag.dll in the populous directory with the one located here [if the download link in this post doesn't work, search through the thread until a workable download is found]:
http://www.gog.com/forum/populous_series/populous_the_beginning_cant_find_videocard/post18

Also note that the AMD 7xxx / 8xxx HD series cards are not compatible with Populous and the atiumdag.dll fix will not work.

Hi!

Disable the compatibility of the shortcut.

Good luck!

The first is not a game breaking error. It simply means that there are no entries in Windows registry. You can still play populous, but some data, including game saves will be saved in C:/POP3.CD folder instead of the game folder.
Like Shukaku said, try re-installing properly.

Second means your graphics card is not recognized. You can follow Shukaku's advice, search this forum for suggestions, or play with Software mode instead. This usually works.

EDIT: Old post I see. Just noticed it.