Just to pre-empt some of the questions that are likely to crop up, could you also provide an idea of the following stuff just to help diagnosis:
- When you say video, do you mean a video clip (eg. a file) or a "live video" clip getting input from a capture card?
- If it's a video file, what format/compression is the video and what codec packs (if any) have you got installed?
- If it's live capture, what capture device are you using and what drivers (eg. manufacturer supplied drivers off a CD or some other source)?
- Does this only happen when you're trying to overlay text on the video, or does it happen always with this video/capture clip?
The red X thing is a directshow "I'm getting no data from the filter graph" thing if I remember correctly, so it could be that the drivers for your capture card (if it's live capture) or installed codecs (if it's a video) aren't sitting happily in the filter graph that's being created for some reason.
Just trying to gather some more info on the problem in case you visit again before Oliver sees this thread :) I'm sure if your problem is soluable then he'll have some suggestions for you!