Effects of compatibility mode
When you open a file from an earlier version in 2007 or save as an earlier version, PowerPoint goes into Compatibility Mode.
More detail on what this means and how it affects your presentations can be found here:
Compatibility mode in the 2007 Office system
Or maybe not. MS has moved everything around again. Rats.
OK. If they won't help, we'll try. More as we learn ...
Tabs in text
Text in PPT 2007 can have individual tab settings per paragraph. Earlier versions allow only one set of tab settings per text object.
When PPT 2007 saves to an earlier format or works in compatibility mode, text objects inherit the tab settings from the first paragraph in the 2007 text box.
Tab settings on other paragraphs are lost.