I have a Sony VAIO VPCF11M1E, with 4GB of RAM, running 64 bit Windows 7 Pro, and I'm using PowerPoint 2003. The laptop has NVIDIA GeForce330M graphics, with the latest drivers, DirectX 11, and the latest Windows Media Player. The laptop is about 8 or 9 months old.

Installed software includes Sony Vegas 9 Pro for video editing (64 bit).

I have been able to build and present PPs with video without any issues until recently. Now, videos can be inserted, but then refuse to play, or may play one time only, then not at all. All vids are located in the same folder as the PP, and all of them play on Windows Media Player, which as I understand it means that the correct codecs must be present. With one particular PP, all the vids worked the first time I presented to a group, but a few weeks later when I went to revise the PP before presenting it again, none of the videos played.

Most (but not all) of the videos were downloaded from YouTube, and converted, and as I say, they all play on WMP but not on PP.

Any thoughts on what might be wrong would be appreciated.