There are supplementary files that need to get installed along with iDVD. To reinstall them you will need to install disk that came with your MacBook Pro. It will look something like this:
First delete the iDVD you have now and then reinstall it and apply all needed updates from here: Apple - Support - Downloads
Thanks for your advice, I have iDVD and themes now. I created a slideshow in iPhoto and shared to iDVD, all looking good. Then I burned it to a DVD. It said it had completed successfully but when I payedit on my DVD player it went halfway through then started at the beginning again. Any suggestions, was the slideshow too big?
Try again but this time follow this workflow:
Once you have the project as you want it save it as a disk image via the File ➙ Save as Disk Image menu option. This will separate the encoding process from the burn process.
To check the encoding mount the disk image and launch DVD Player and play it. If it plays OK with DVD Player the encoding was good.
Then burn to disk with Disk Utility or Toast at the slowest speed available (2x-4x) to assure the best burn quality. Always use top quality media: Verbatim, Maxell or Taiyo Yuden DVD-R are the most recommended in these forums.
If the disk image will play as you intended then it should burn to disk and play satisfactorly in a DVD player. There is a 99 slide limit in slideshows but exceeding that usually results in a pause for a bit before continuning. How many slides do you have in the slideshow?
There's a 99 chapter/slide limit for video DVDs. Apple gets around that limitation by renumbering slide 100 back to 1. At that point the DVD will pause a bit. Different DVD players will be affected differently. My high end Sony DVD player pauses longer than my inexpensive Sony DVD/VHS player. Go figure.
The workflow I suggested does help minimize the pause but can't eliminate it entirely.