Nero turns .iso files into "empty" CDs

It seems like whenever I use Nero to burn an .iso file, I end up with a “blank” CD. By “blank” I mean that Explorer says the CD has 0 bytes on it, and the CD is always named “Cd”, instead of its correct name.
I tried looking at the most recent bad CD with IsoBuster, and it says the CD has one Session and one Track (which is about 658 MB).
Is there some setting in Nero that makes it automatically think that all .iso files are Audio CDs or something? I don’t have this problem when making new data CDs or burning BIN files. Does it make any difference (in this case) if I use TAO or DAO?

Please tell me if you know what the deal is.

I’m using Nero 5.5.8.0 on Win98, burner is HP CD-Writer+ 9500.

One thing I’d chect is to be sure you checked “close disc” or “finalize disc”

I checked Finalize Disc. When I’ve tried not checking it, Nero prompted me to turn off multi-session, or DAO (or TAO, I forget which).