An 780 MB disc is a nonstandard length. A 90 minute disc should be able to record up to 791 MB. In any event, any disc over 700 MB (80 minutes) must use Nero overburn settings to allow it to be burned. Use the following settings for a data disk:
1. Don't use the Nero Wizard. It will not allow overburning as it defaults to Track-At-Once. If it is active, close it.
2. Multisession | No Multisession must be checked
3. ISO | Check Mode 1 and Joliet
4. Burn | Check Write and Finalize CD (No further writing possible). Write method must be Disk-At-Once.
5. In the main menu, File | Preferences | Expert Settings check "Enable overburn disk-at-once burning". If you are using a 780 MB data disc, you can set the Maximum CD length to 88 minutes 45 seconds 0 frm. Hit Apply, then OK. You can also use the overburn capacity test in Nero CD Speed to estimate the maximum overburn capacity if the firmware of your burner permits a successful test.
6. The Red and Yellow marker settings in File | Preferences | General Settings have no effect on burning or overburning. They are there just as a visual aid.