Open your dvd directory (created by dvdbackup) with pgcedit (a Windows program)
Go to the Title menu, and select 'rebuild all time maps of dvd'
Save
Move the PgcEdit_backup directory in VIDEO_TS to someplace else
Re-try your previously failed mkisofs
You might try the following as a work-around:
Open your dvd directory (created by dvdbackup) with pgcedit (a Windows program)
Go to the Title menu, and select 'rebuild all time maps of dvd'
Save
Move the PgcEdit_backup directory in VIDEO_TS to someplace else
Re-try your previously failed mkisofs