>What would cause a data cd with an AUTORUN.INF file to be opened in explorer as an audio cd? (WIN 98)

One cause I've seen in the past has been an older CD-ROM drive that predates CD-R may have trouble with CD-Rs written in other than the ISO standard format by some CD-RW drives. The solution in the past has been to resort to less flexible CD creation tools that always pre-master the output and write in the ISO format, like EZ CD Creator rather than using something like DirectCD to create them. A PITA, but understnadable, and well-documented on Adaptec's CD-R web site.