A problem with this seems to be that if you used nested veg files on the timeline that the media included in those nested veggies does not get copied. If you the remove the original material you are SOL.
Are you sure all other programs are shut down, even those running in the background. Might downlaod EnditAll. I use this program to shut down everything on my computer when I go to work with Vegas.
Edward said he was not familiar with Studio which is the watered down version of Vegas and is what you apparently have. He is VERY familiar with the full fledged Vegas program!
Double left click the event. Then look at the lower right hand corner of the time line. There will be three times listed there. The one on the far right will be the length of the clip.