Export Problem

Hi: Not sure the best spot to ask this but here goes.

I am running Vista HP. My issue is with exporting my video clips to a DVD. I have always just popped in a DVD and moved the files. I could also move them back onto the system if desired. However, all of a sudden, the video clips are exporting to a weird format (vob and a few others) and then when I look at the DVD content on the D drive, the video thumbnails will not play. I also can not pop the DVD into a player attached to the TV to play...I get "invalid disk" errors. This has never happened before. The clips play fine on the computer. They seem to just be exporting weirdly. Can ANYONE tell me what is going on please and how to fix this? Thank you!