Are you installing over a network? Is your installer a Installscript, Installscript MSI, or pure MSI project?
I've had issues with people installing over a local network and they either lose connection or there's a hiccup. Not sure if this is the same issue.
If I'm not mistaken, there is a switch that will tell the *.exe to cache unpacked installer locally. If it will help I can look it up.
I've noticed that sometimes images won't appear during installation or uninstallation when launching the *.exe from a networked location (mapped drive or network address). Certain cached files won't work over a network.
