Had someone try a QDK compiled .CAS file and I think their nero software thought it was something else and prompted them something like "Nero burning rom?"

I don't know why Nero should be wanting to open CAS files. There are a few other applications that might want to use a .CAS extension according to http://filext.com/detaillist.php?extdetail=cas but Nero isn't listed. Anyway, it sounds as though Nero has associated itself with .CAS files. You can easily get Quest to "steal" them back, by going to the Options window, then Other, then click the "Restore File Associations" button. This will associate Quest with .CAS files again, so when you double-click them, Quest will open the file rather than Nero (or anything else).

Thanks. Had another nero user who said they had no problems at all with .CAS files. So I don't know what the problem is/was.