Is anyone else having this problem? I saw a thread about it in the Cartography section of the forum, but there weren't any solutions that would work for DDP when using Python to export hundreds of grid maps (as we're doing). Basically, almost every .PDF I export has labels showing up way outside the data frame, such as in the legend, title, etc. Some are worse than others and there seems to be no rhyme or reason to it. We are running ArcGIS 10, SP3 on Windows 7, 64-bit.
Here is an example of one of the maps (labels outside the data frame are circled in red):