Hi RiverQueenMama and welcome to cdfreaks,
Few thoughts to add to Mack's suggestions.
Navigate to your temporary directory, is the file you ripped still there, how large is it? If you have clutter, leftovers, etc., I would delete all of it.
If you need any of this data, another option is to change/create a temp folder in another location on your hdd. If you are unable to locate previously ripped files, just uncheck "delete temporary files when finished" in "common settings". You can also choose another location on your hdd as the "target", instead of your burner. Then, re-rip. This way you can look at/manipulate the files and we can figure this out.
Also, take note of your "target size". This should be "dvd5" and the ripped file size should not exceed the specified size...default is 4300 MB...you can alter this setting.
Hope this helps.