Quark 6.5 Updater sort of fails

Yes, we still have to keep stupid Quark 6.x around for older work. So I'm repackaging it. I've taken a modular approach up to now - lay down 6.1, lay down 6.5, then create Preferences folder in the /Applications/Quark Xpress folder (they recommend it for 'performance' reasons). I created the packages on Tiger. All three go down fine on PPC & x86 Tiger InstaDMG builds. On Leopard, I get this fun little message: [i]installer: The install failed (The Installer is experiencing errors installing onto “InstaDMG_Temp”. The disk may be damaged. Please try installing on another disk.)[/i] Yet when InstaDMG finishes and the image is deployed to a workstation, Quark *6.5* launches and works. I've tried re-packaging the update on Leopard and had some PackageMaker weirdness. As I write this I realize, I could just package up the completely updated and configured Quark install into 1 pkg installer. But mainly I want to know - what's up with the 'disk may be damaged' business? Has anyone encountered similar behavior?