This has been seen when trying to record more than 24 tracks with Pro Tools online and slaving to timecode with the preference "record online at insertion/selection" selected. Selecting this preference is similar to preroll in that it uses roughly twice as much bandwidth. This can be seen by viewing the PCI load meter in the automation enable window.Selecting "record online at timecode (or ADAT) lock" instead frees up PCI bandwidth and allows for a higher track count without the dreaded -6042 error.