When DLP agent blocks sensitive content written to a .ppt file located on a network share, the .ppt file becomes unusable.
This issue occurs on machines running version 12.0 DLP Agents and Microsoft PowerPoint 2003 with Allow fast save enabled.
Upgrade your version of Microsoft PowerPoint to any version (including hot fixes) greater than PowerPoint 2003. If you cannot upgrade, disable the Allow fast save option in PowerPoint.