Why does DB2 uninstall result in "cannot find path"?

We have a standard DB2 10.5.0.4 installation on Windows 2008 Server. If we try to uninstall this with db2unins.bat , we always get the error message "The system cannot find the path specified." The message seems to be printed at the very end of uninstalling.
The uninstallation process itself is actually successful, so it's basically OK. However, we want to automate this (UrbanCode Deploy) and an error message really disrupts us here.
Any hints appreciated!