Weird problem while installing Adobe After Effects CS 4. Help me!?

I am trying to install the Adobe Creative Suite 4. Every thing works fine except the installation of After Effects and Illustrator. The problem is that I can't even select (check) the After Effects option from the custom install option of the setup. All the check marks are normal except it. But surprisingly when I see the payloads folder where all the files and setups of the software are, I can see all the files required to install After Effects are normally there. Why isn't the setup installing it then? Or at least why cant I check mark the After Effects installing option from the setup? Has anybody experienced such issue? Screen shot attached.