So, after wrestling with a Roxio 7 uninstall, I finally had enough and took a wrench to the MSI.
"The InstallScript engine on this machine is older than the version required to run this setup. If available, please install the latest version of ISSript.msi, or contact your support personnel for further assistance."
Tried installing ISScript v8, but that was a no go.
Wound up installing ALL of the ISScript drivers. Still nothing.
Turns out that Roxio used a completely different version of the ISScript v8 engine for EMC. Utterly incompatible with the official v8, and also unavailable in anything but Roxio products. I fetched it from another machine here, since I've long lost/thrown out the Roxio 7 disc.
If you're having this problem, PM me and we can work out a way for me to send you the *proper* version of the InstallScript engine.
If you'd like to go looking for it yourself, the "proper" Roxio-installed version of ISScript.dll is 8.1.0.304. The official version from InstallShield is 8.0.0.123. You can find your version by looking in "%ProgramFiles%\Common Files\InstallShield\Driver\8\Intel 32", right-clicking ISScript.dll, and clicking on the Version tab. (alternately, you can just hover the mouse over the file in Explorer to see the version number)
