I am experiencing also. My searching of the net indicates a conflict with Tiger and all versions of iDVD although version 5 might work better. There are several things to try including deleting the preferences file, clearing caches, increasing the size of your hard drive (which you tried). I have not tried all these yet and I would have to re-search to find the details (exactly which file is the iDVD plist file - apple.com.idvd.plist I think).
In iDVD 5 you can burn to a file instead of a DVD. In lower versions there is an easter egg for doing the same thing (details are on my other computer), but if you search you should find. Then you can use the Disk Utility to copy the DVD file onto a blank DVD, and this works. So if you can get it to run once you should be good for multiple copies. I spent an entire day making 10 copies between all the quits.