.MSI并不总是卸载以前的版本

In a number of applications we create an MSI Installer with the Visual Studio Setup Project. In most cases, the install works fine, but every now and then the previous version was not uninstalled correctly. The user ends up with two icons on the desktop, and in the Add/Remove program list, the application appears twice. We have yet to find any pattern and in most cases the installer works without any problems.