i only have two drives installed at a time, i use one for ripping and one for burning. i have not had the ripping drive open for burning. so i have not actually experienced your particular problem.
i have a possibly related problem when burning. the first and second rip/burn goes normal. dvdfab will automatically open ImgBurn and start the burning. the third rip/burn dvdfab will open the Burning Speed Selection Box. not a real big deal because i can close dvdfab in between rip/burns to remedy the problem, or just wait 30 seconds for the dialog box to automatically select ok.
fengtao is looking into the dvdfab decrypter problem with creation of ISO, i will also ask fengtao about this particular behavior.