I have a strange behavior on a Basic MSI package. It's an old project (couple of years) where at one moment I had to add a new file / component. It's nothing special about this file, an Interop dll, no registration, no COM, copied in the same folder like all the others.
Since I added this file, after the uninstall this dll is consistently left on the target machine. I removed it and I put it back, but it did not help.
One thing you want to check on is the file's properties in InstallShield. Sometimes if it is marked as "permanent" it will get left behind on uninstall. Or if something else references it too.
I found out that the dlls are registered on target machines in SharedDLLs with counter > 1, probably from older tests. I cleaned up the registry and everything is correct.
