Just finished installing on a Winserver 2008 platform. It took a couple of shots to get it right so I thought my experience may be helpful for someone else.
Firstly on my platform the install is slow, be prepared for this, allow about 15 minutes.
On the first pass I left a web browser open and while the install was happening I went to use it. An install error dialog box came up, agent.exe.6ED2386... is not marked for installation. Closing the dialog terminated the installation.
I tried again and this time the install went through to a point of saying 0 minutes left. It sat like that for about 15 minutes. Task Manager showed that VSStudio 2010,2012 and 2013 were given bursts of activity. I am assuming that the install was integrating CR into these programs. A warning message saying please wait integration is proceeding may be more appropriate than 0 minutes left.