When an optional package fails to install, this text is presented:
"The configuration process will continue but some parts of ThinLinc might not work correctly."
Although technically correct, to continue you have to press back twice and uncheck the box to install this package. We should either allow it to continue directly, or change the phrasing to make it clearer that you have to go back first.
We need to consider both text mode and graphical mode when resolving this. In text mode you don't have to "go back" somehow in order to continue with the installation.
*** Bug 7628 has been marked as a duplicate of this bug. ***