Im in vegas 9 pro on an xp machine

Here is what happened:
1. edit video
2. watch video from time line, everything looks good
2a. there may have been a close vegas and reopen here, im not sure, there were two of us working on the project
3. render to mpg2
4. close vegas
5. watch render. the audio is missing on one clip in the render, and strangely, the text in a lot of the titles has changed to text from other projects, or to a video clip. So, for example, if there was a title that said "Jane Smith" in 15pt arial with a custom position, now it says "music by cass harris used with permission" in 14pt times bottom left. The weird thing is that the "music by" text is from another project. Another text event switched to a random video clip from the project.
6. open vegas and look at the timeline, the timeline does reflect the incorrect clips and text. In other words, its not like something happened during the render to build the rendered file wrong but the time line was still right, something happened to the timeline to switch things out before the render.

so, for this project i will go in and correct everthing and see what happens. But for the future, any ideas what could cause this? and more importantly how to keep it from happening again?

thanks!