My son bought Lightroom 4 Student Edition, provided his school ID and received a serial number. We had to upgrade our Microsoft to be compatible, then had other computer problems, but the driver still won't even recognize that the installation CD has been inserted. Is it still a computer problem or a defective CD?
My answer won't help with your actual problem (which probably can only be resolved by the PC manufacturer's or Adobe's support), but in the meantime: Download the Lightroom 4.1 update from Adobe (downloads -> product updates -> Lightroom - Windows -> Lightroom 4.1), which you should do anyway (because on the CDs is still LR 4.0 AFAIK). The update is the same as the full version and does not require the original installation disk. After installation, it should accept your serial number (which stays valid for later updates, too).
It might be a bad disk, or you might have problems with some of your hardware. It would be hard to tell. But you don't need the disk anyway. Just download Lightroom from the Adobe website and install it. It will start up as a trial version. But all you have to do is indicate that you have a serial number and you will be presented with a dialog where you can enter the number that you have. Then you will be good to go. The trial version is the full version of the program, but with a 30 day time limit. Once you have entered the serial number the time limit goes away.
By the way: Why does Adobe require an Adobe ID to dowload the trial version, but everybody can simply download the fully functional update without any registration? Is that a legal problem? I always wondered about that (and if it is "legal" to download an update for an initial installation). @skbmt: Just to be sure, you may want to download it "officially" as a trial using your Adobe ID.
Perhaps I think too much