it was not your fault that you couldn't find the error ring cause it's been removed during the development of LabVIEW 8. Unfortunately we forgot to document it in the upgrade note. Sorry for that!
Best regards,
Carsten Sprung Applications Engineer National Instruments Germany
unfortunately I haven't any additional information concerning this issue. I know that it's been usefull in some situations therefore I was as surprised as you when I found out that it is gone.
I'm not sure if this helps, but page 13 of the LV 8.0 Upgrade Notes has this bullet: "In LabVIEW 8.0, the error ring constant is not on the Functions palette. Use a 32-bit signed integer constant instead to enter the error code that you want."
Kelly H LabVIEW Documentation National Instruments