First, tell us all about your computer. The more detail, the better. Pay special attention to your hard drives, how they are used, their free space and their type and speed.
Next, tell us all about your Project. Give specifics on your Assets, their format, CODEC's used, sizes (especially for stills), Duration and what Effects you might have used. If you need help getting specs on your Assets, download and install the freeware program, G-Spot. It will give you full details on all of your AV Assets. For still, you can get that from the Properties Panel in the your Project.
Last, tell us about what other programs you have running all of the time. Going to Task Manager>Processes tab will give you a list of everything running. A screen-cap of that will help and save a lot of writing/typing. Within the list of programs, also make mention of any programs, like Nero, Roxio, etc. One of these could well be the cause that your burner is not being seen by PE. Let's address other issues first, but I think we can probably get your burner back.
While you are gathering up this info, take a close look at the FAQ's on this forum. There are a lot of good tips on setting up a computer for NLE work, and also optimizing Vista. It seems a good OS, but needs some work, from its default installation.
Good luck, and we'll all look over your info. There are probably a dozen places that someone can help you,
You need at least PE v3.0.2 to run with Vista.
Any version before that will not be stable under Vista, and will only cause you heartache...