Unfortunately, I have the same problem as the original poster of this subject:
JOINERPC - "A checksum error occurred while joining the segments. Probably on of your CDRoms is corrupted, please contact your distributor."
I have contacted Spectrasonics tech support and they haven't been able to provide a solution. As I'm on XP (which was explained in my original e-mail to tech support), the suggestion to follow the OSX install instructions for error ID-61 wasn't much help After explaining AGAIN that I'm on XP, the instructions were to install in Safe Mode. That didn't work, either.
I have this same install problem with BOTH Atmosphere and Trilogy. It's especially irritating to sit through 40 minutes and 4 discs of the Trilogy install and then get the error. The problem is, sometimes it happens on disc 1, sometimes on disc 4. With Atmosphere, it happens either on disc 1 or 2 (I've never made it past disc 2).
So, what do I need to do? Do I have to make copies of ALL the install discs? Any other thoughts or suggestions? This is getting rather old, I must say...